Active Autowerke N51 Headers w/BMW PE - Install, Troubleshooting & Thoughts

[crowtrobot]

Towards the end of last year, I briefly flirted with the idea of upgrading from my 128i to a 135i, then an E92 M3, but after a few months of searching and thinking, I decided I was at home in my 128i and decided to dump some of that potential down payment into upgrades instead. I already had the BMW Performance Exhaust installed, and wanted to keep to OE upgrades, but the performance increase seemed to good to pass up, so I purchased it back in January to commit myself to a plan and get off the car shopping kick. Had some questions before ordering which were promptly answered by Rob @ AA (more on this later) and was given a great deal on the parts & tune.




Before starting the install, I made sure to order an extra set of studs for the mounting of the headers to the cylinder heads (part #11127593376, qty: 16). Ordering these extra is STRONGLY RECOMMENDED. My car has been in the northeast its whole life, and many of the stud nuts holding the OE manifold in had corroded and fused themselves with the original studs, so most of them came out together. AA provides 16 new nuts and 4 bolts/nuts for the exhaust flanges.

Did the install in a helpful friend's garage on jackstands. SEVERELY underestimated the time it would require to do this job. Took us around 10hr to complete the job due to some complications, pitfalls and needing some better tools.

For starters, the workspace is very cramped. I made another thread asking about how best to attack the stud nuts for the manifold - I would highly recommend a flexible-head ratchet and a flexible box wrench. I'm pretty certain there's no way we could have completed the job without that flexible box wrench, though maybe one with an offset would suffice. As I mentioned, the car has been in the NE, and seen plenty of salt/snow, so the exhaust manifold-to-straightpipe flanges were also fused together, along with the bolts. Due to the cramped space, getting these apart was no simple matter either.




First thing to disconnect were the O2 sensors. I taped off both sides of each connection to make sure I didn't screw up which sensor went where when we re-installed. I put one piece of masking tape on both sides of the connection for one bank, and two pieces of tape for the other. Left the sensors plugged into the original manifolds and pulled the cables when taking the manifolds out to make removing the sensors from their sockets a little easier.




We double-teamed the stud nuts, one person underneath, one person with an arm down the engine bay from above. We generally needed one person to guide the socket/wrench onto the nut, and the other person to wrench on it, so highly recommend having two people for the job as well.

Once all the nuts were off, getting the old parts out, and the new parts installed was just a matter of will and figuring out how to contort our hands to get access.

After everything was put together, buttoned the car up and started her. HOLY CRAP it was loud. I mentioned the questions I asked AA before ordering - one of the questions I had asked was what the NVH impact was going to be like given that I had the PE, I was concerned about it being loud, and they had said that it would be "minimal", but this was far from minimal. Sounded pretty badass, but had an incredible resonance from ~2000-2400 rpm that rattled my windows and floorboards. While the performance increase was awesome, the volume increase made me quite self-conscious driving home, wasn't exactly what I was hoping for after hearing such good things about these headers. The car also picked up a nasty idle surge that was causing the car to jump from ~600-800rpm and shudder pretty badly. The next day, after driving to work and sitting in the parking lot, car threw codes: 29D1, 29D2, 29D0, 29CC, 29CD - Misfires cyl. 5, 6, 4, Multi, 1. Cleared the errors with AA's Simon3 tool and they did not come back, but I was hesitant to drive the car a whole lot at this point.

I went through about a week of back-and-forth with Nic @ AA (very responsive and helpful) trying to troubleshoot the idle surge and potentially get at the root of the volume/resonance as well. I tried resetting the throttle adaptations using the instructions on AA's website, and the instructions on these boards (which vary slightly in how the throttle comes into play during the process). Retorqued the exhaust bolts, verified my O2 sensor connections several times over, took apart the EVAP system in case we had bumped a hose or something - no dice. Finally, today I think I made some progress:

Last night, I had installed a new M-sport steering wheel (courtesy of idk alex great seller!) and had the battery disconnected while doing so. This morning when I started the car, the idle-surge was gone. Car was still loud as hell, but the rough idling was gone, so that was a relief. Not sure why this is, but my guess is that maybe that *actually* reset the throttle adaptions?

I also removed the BMW PE and reinstalled the OE exhaust. Huge difference! When AA said that the NVH impact would be minimal, this is what they must have meant - could barely tell the difference from stock. I'm a little sad to lose the PE (I really liked the tone and look of the pipes), but I'm very happy to get back the liveable volume and retain the performance bonus of the headers.

In summary: AA has been a good company to work with, both for the purchase and their support. Headers definitely give a performance boost (have not dyno'd but plenty of others have). If you have a BMW Performance Exhaust, be forewarned - this upgrade will make your car loud as shit.

Sorry for the long post, but I just wanted to capture my thoughts and problems in case someone else goes searching for the same thing and has problems.

Cheers!

[2010MSPORT335i]

Love the writeup...

From a previous 35i owner, I think the 128's are under appreciated. Low weight, NA I6, Manual, RWD.

Glad you had a productive weekend.

[asbrr]

Great post!

So do you also have the matching AA tune to give you full benefits of the 3 stage intake manifold? You should be making good power now...

On the exhaust front, yes the PE + Headers is known to be really loud....one cheap alternative would be to replace your stock rear muffler with a 135i box, and do the golf tee mod. That combo should be quite nice and liveable...

[crowtrobot]

Originally Posted by asbrr

Great post!

So do you also have the matching AA tune to give you full benefits of the 3 stage intake manifold? You should be making good power now...

On the exhaust front, yes the PE + Headers is known to be really loud....one cheap alternative would be to replace your stock rear muffler with a 135i box, and do the golf tee mod. That combo should be quite nice and liveable...

Yessir, I had purchased a tune from AA last year, so they worked with me on the tune for the headers and the 3-stage intake. Definitely feel more of a "sucked into the seat" feeling at WOT.

w.r.t. PE + Headers - I searched quite a bit about volume before ordering (and asked AA as I mentioned), but unfortunately didn't find anything definitive. I asked a few people directly after the fact and they said "oh yeah, totally loud", haha, so my hope was to put this up for posterity in case someone else searches for that combo.

w.r.t. 135i box - are the muffler internals different? I thought the stock 135i box just had different tips. That would be a good, cheap alternative. Like I said in the big post, I'm a little sad to have to choose between liveability and that PE noise now. Day-to-day the PE is a great mod, for anyone on the fence about it.

On to intake and brakes now before the track season starts...

[asbrr]

Originally Posted by crowtrobot

w.r.t. 135i box - are the muffler internals different? I thought the stock 135i box just had different tips. That would be a good, cheap alternative. Like I said in the big post, I'm a little sad to have to choose between liveability and that PE noise now. Day-to-day the PE is a great mod, for anyone on the fence about it.

On to intake and brakes now before the track season starts...

They are different - the internals on a 135 box are not baffled, if you dig around in the forums someone cut one open to verify. I can tell you it does sound different, deeper than the stock back box. It's not a huge change but was what I was looking for for a daily driver. On top of that they should be pretty cheap to find....

Other options are Magnaflow, I think bimmerbob has a full magnaflow setup with AA headers and he is quite happy (video posted in this build thread also).

[Suhb]

135i muffler is louder than the 128i. I definitely love the 135i exhaust paired to the AA headers. The set up of the OE mufflers do an excellent job with low rpm drone but still open up really well above 4.5k. No other set up helped quell the drone from AA headers. I'm going to hack off my secondary cats to add more volume. I'll get an exhaust vid up here when I do.

[asbrr]

Originally Posted by Suhb

135i muffler is louder than the 128i. I definitely love the 135i exhaust paired to the AA headers. The set up of the OE mufflers do an excellent job with low rpm drone but still open up really well above 4.5k. No other set up helped quell the drone from AA headers. I'm going to hack off my secondary cats to add more volume. I'll get an exhaust vid up here when I do.

Right! I forgot you had done this.....man I am so tempted to do the AA headers........priorities...

[STR8-6IX]

you really need to get a tune for these headers.. it is important.

[TGel15]

Originally Posted by crowtrobot

Towards the end of last year, I briefly flirted with the idea of upgrading from my 128i to a 135i, then an E92 M3, but after a few months of searching and thinking, I decided I was at home in my 128i and decided to dump some of that potential down payment into upgrades instead. I already had the BMW Performance Exhaust installed, and wanted to keep to OE upgrades, but the performance increase seemed to good to pass up, so I purchased it back in January to commit myself to a plan and get off the car shopping kick. Had some questions before ordering which were promptly answered by Rob @ AA (more on this later) and was given a great deal on the parts & tune.

Attachment 1580444
Attachment 1580445

Before starting the install, I made sure to order an extra set of studs for the mounting of the headers to the cylinder heads (part #11127593376, qty: 16). Ordering these extra is STRONGLY RECOMMENDED. My car has been in the northeast its whole life, and many of the stud nuts holding the OE manifold in had corroded and fused themselves with the original studs, so most of them came out together. AA provides 16 new nuts and 4 bolts/nuts for the exhaust flanges.

Did the install in a helpful friend's garage on jackstands. SEVERELY underestimated the time it would require to do this job. Took us around 10hr to complete the job due to some complications, pitfalls and needing some better tools.

For starters, the workspace is very cramped. I made another thread asking about how best to attack the stud nuts for the manifold - I would highly recommend a flexible-head ratchet and a flexible box wrench. I'm pretty certain there's no way we could have completed the job without that flexible box wrench, though maybe one with an offset would suffice. As I mentioned, the car has been in the NE, and seen plenty of salt/snow, so the exhaust manifold-to-straightpipe flanges were also fused together, along with the bolts. Due to the cramped space, getting these apart was no simple matter either.

Attachment 1580446
Attachment 1580448

First thing to disconnect were the O2 sensors. I taped off both sides of each connection to make sure I didn't screw up which sensor went where when we re-installed. I put one piece of masking tape on both sides of the connection for one bank, and two pieces of tape for the other. Left the sensors plugged into the original manifolds and pulled the cables when taking the manifolds out to make removing the sensors from their sockets a little easier.

Attachment 1580447
Attachment 1580449

We double-teamed the stud nuts, one person underneath, one person with an arm down the engine bay from above. We generally needed one person to guide the socket/wrench onto the nut, and the other person to wrench on it, so highly recommend having two people for the job as well.

Once all the nuts were off, getting the old parts out, and the new parts installed was just a matter of will and figuring out how to contort our hands to get access.

After everything was put together, buttoned the car up and started her. HOLY CRAP it was loud. I mentioned the questions I asked AA before ordering - one of the questions I had asked was what the NVH impact was going to be like given that I had the PE, I was concerned about it being loud, and they had said that it would be "minimal", but this was far from minimal. Sounded pretty badass, but had an incredible resonance from ~2000-2400 rpm that rattled my windows and floorboards. While the performance increase was awesome, the volume increase made me quite self-conscious driving home, wasn't exactly what I was hoping for after hearing such good things about these headers. The car also picked up a nasty idle surge that was causing the car to jump from ~600-800rpm and shudder pretty badly. The next day, after driving to work and sitting in the parking lot, car threw codes: 29D1, 29D2, 29D0, 29CC, 29CD - Misfires cyl. 5, 6, 4, Multi, 1. Cleared the errors with AA's Simon3 tool and they did not come back, but I was hesitant to drive the car a whole lot at this point.

I went through about a week of back-and-forth with Nic @ AA (very responsive and helpful) trying to troubleshoot the idle surge and potentially get at the root of the volume/resonance as well. I tried resetting the throttle adaptations using the instructions on AA's website, and the instructions on these boards (which vary slightly in how the throttle comes into play during the process). Retorqued the exhaust bolts, verified my O2 sensor connections several times over, took apart the EVAP system in case we had bumped a hose or something - no dice. Finally, today I think I made some progress:

Last night, I had installed a new M-sport steering wheel (courtesy of idk alex great seller!) and had the battery disconnected while doing so. This morning when I started the car, the idle-surge was gone. Car was still loud as hell, but the rough idling was gone, so that was a relief. Not sure why this is, but my guess is that maybe that *actually* reset the throttle adaptions?

I also removed the BMW PE and reinstalled the OE exhaust. Huge difference! When AA said that the NVH impact would be minimal, this is what they must have meant - could barely tell the difference from stock. I'm a little sad to lose the PE (I really liked the tone and look of the pipes), but I'm very happy to get back the liveable volume and retain the performance bonus of the headers.

In summary: AA has been a good company to work with, both for the purchase and their support. Headers definitely give a performance boost (have not dyno'd but plenty of others have). If you have a BMW Performance Exhaust, be forewarned - this upgrade will make your car loud as shit.

Sorry for the long post, but I just wanted to capture my thoughts and problems in case someone else goes searching for the same thing and has problems.

Cheers!

Have you had any bad experiences with the AA tune?
I am hesitant to tune as I have seen many people on the forums having issues (surges, idling etc.) and those issues are not worth the improved drivability IMO.
Turner motorsports is located nearby and offers a SULEV N51 software but I'm pretty sure it is just the AA tune

[crowtrobot]

Originally Posted by TGel15

Have you had any bad experiences with the AA tune?
I am hesitant to tune as I have seen many people on the forums having issues (surges, idling etc.) and those issues are not worth the improved drivability IMO.
Turner motorsports is located nearby and offers a SULEV N51 software but I'm pretty sure it is just the AA tune

I have heard the same (that Turner's is just the AA tune), though I got my tune from AA and installed myself using the Simon3 tool, so I can't confirm that Turner's is the same thing.

Since I reset the adaptations by way of disconnecting the battery, I have not had any driveability issues or bad experiences. I have noticed that when the car stops, like at a light or stop sign, I'll get an extra pulse or two of idle surge, but nothing severe like I had when I first did the install of the headers. If you can imagine coming to a stop sign: brakes->clutch in->full stop, it'll rev up from ~500 to ~800 once, then 500 to 600, then idle normally. This does not happen every time and I don't remember this happening when I only had the tune (no headers) either.

Just reinstalled the BMW Perf. Exhaust since I'll be at the track this weekend: still friggin' loud. Installing the Perf. Intake seems to have changed the sound somewhat and maybe reduced the drone a little, but with the PE, it is still loud and drone-y around that 2400rpm mark. On the upside, it's making my fuel economy better since I'm driving in 6th gear all the time to keep the noise down!

[Bimmer-Bob]

Originally Posted by crowtrobot

I also removed the BMW PE and reinstalled the OE exhaust. Huge difference! When AA said that the NVH impact would be minimal, this is what they must have meant - could barely tell the difference from stock. I'm a little sad to lose the PE (I really liked the tone and look of the pipes), but I'm very happy to get back the liveable volume and retain the performance bonus of the headers.

In summary: AA has been a good company to work with, both for the purchase and their support. Headers definitely give a performance boost (have not dyno'd but plenty of others have). If you have a BMW Performance Exhaust, be forewarned - this upgrade will make your car loud as shit.

I somehow missed this post when it was new, but a few thoughts:

- I went from the stock headers + BMWPE ---> AA headers + MagnaFlow cat-back in a single step, so I have no idea what the AA headers + BMWPE combination sounds like, but I had heard it was loud. Your experience just reaffirms my decision - it seems to be the unanimous consensus that this is not a daily drivable setup, which is pretty telling, because I think many (most?) of us are not the type to shy away from a little bit of car noise.

- I totally get missing the BMWPE sound! It's really so very perfect. Almost unbelievable that it's an OE part (I'd be very interested in knowing who made the part for BMW). If you're looking for a replacement to match the AA headers, I'd suggest considering the MagnaFlow cat-back. It's a little more subtle than the BMWPE, but that actually works with the headers, plus fitment is nice. I think it's a pretty sexy, refined sound, but I admit I do still miss the rawness of the BMWPE. SuperSprint has a modular muffler, resonator (or delete), cats (or straight pipes), and header system available for our cars - I bet any of those parts would work nicely with the AA headers as well, of course they're not exactly cheap! I'm not aware of any other quality off-the-shelf solution.

- The idle surge is no joke! It was worst for me after fitment of the headers and before the tune. Since tuning, it seems to come and go, and is pretty inconsistent. Lately it seems to be back with a vengeance, but I'm also throwing eccentric shaft sensor codes, so I'm going to need to rule that out first. I changed batteries not too long ago, and have reset throttle adaptations several times (in several different ways!), so that hasn't been helpful for me. If a new eccentric shaft sensor doesn't fix the issue, I might consider trying the BPC tune, although I'm not eager to spend $600-$700 on something that might not even fix the issue, and I'd like to hear some user reviews before I drop that kind of cash.

[carscatscoffee15]

Crap, do you guys think the sound difference between the AA exhaust + tune + headers would be the same (in terms of loudness) to OPs set up of AA headers + tune + BMW PE? I couldn't find anything solid with a sound clip that didn't have the Stage III manifold upgrade as well so it was hard to find anyone that had this (or something close done) until I found this thread

[carscatscoffee15]

Also hi! That was my first post. I came from an E60 (RIP) and had the chance to purchase one of the cars of my dreams (seriously) so I am new to the E82 community. I went with the 128i due to my familiarity of the N52 engine

[Suhb]

AA muffler + AA headers is quieter than the AA + PE combo. But AA muffler also has a drone around 2400-2800 that is loud enough to rattle some interior bits.

[carscatscoffee15]

Originally Posted by Suhb

AA muffler + AA headers is quieter than the AA + PE combo. But AA muffler also has a drone around 2400-2800 that is loud enough to rattle some interior bits.

Thanks for the quick reply! I've been searching high and low and most people do report drone.. if that's the case then I'll ask my shop to hold on to the OE exhaust. I'm thinking about doing the euro box later in the year as I have spent a bit on this car at once (also got rid of the run flats) but I hope I am happy with the results

I also am coming from a bone stock E60 528 so this in itself is a big improvement for me and I'm more than happy

[Eins Suchtig]

Originally Posted by Suhb

AA muffler + AA headers is quieter than the AA + PE combo. But AA muffler also has a drone around 2400-2800 that is loud enough to rattle some interior bits.

Yep the drone is there but I love the overall sound!
PD: I just drive 13 miles/day