135i (N55) Exhaust on 128i (w/ Secondary Delete)

[Driven5]

No, not just the muffler. The whole thing...Or near enough to.

I picked up a cheap stock exhaust from an N55 135i for a bit of an experiment.



At first glance, I thought that I might be able to actually adapt the 135i exhaust straight to the 128i manifold outlets.







While I still have a couple of ideas on how it might be possible, I decided to take the path of least resistance. So I started selectively cutting and welding, until I had my franken-midpipe.



It's the 128i factory pipes until just aft of the forward clamp mount. That means one tube is 50mm, and the other is 55mm, both with 1.5mm walls. The 135i tubes are both 60mm with 1.5mm walls. The less gap the better with welding, and 2mm of slop was already pushing the limit of my welding 'skills'. So I cut an extra piece off the excess 55mm tube and used it as a means of stepping up the diameter of the 50mm tube. Each joint has a couple inch overlap, so it all slipped together and held itself in place on the car while I tacked it, before removing it from the car for final welding. There is also a 'squished' (oval) area in the 60mm tubes that's a little too narrow across the flattened sides for the 55mm tubes to slip into that I had to avoid, with the single weld side mating before it and the double weld side mating behind it.



I can't say whether this sounds louder/quieter or better/worse than a PE or muffler delete, but I can say that I at least now finally have a car that is audibly engaging to drive. It's plenty quiet and neighborly at light throttle, and has a nice satisfying growl beyond that. A few burbles and light pops on certain decel's. No drone. In fact, it still almost seemed a little too quiet at first. But honestly, for my 'stock plus' intentions, it's probably just about perfect... The 'sport exhaust' it should have been available with from the factory.

Now to figure out how to get a video with some decent audio to post up, beyond just some free revs in the driveway.

[Nixis]

got a vid?

[Driven5]

Unfortunately, this is all I've been able to come up with so far...

I'd love to find somebody in the Seattle area with a muffler delete or PE on a 128i that I could get a direct comparison with..But I'm not going to hold my breath. Even if left to my own devices, I'll still eventually get something better and post it up, but possibly not until after opening up a little extra intake noise as well.

[markslc1]

Originally Posted by Driven5

Unfortunately, this is all I've been able to come up with so far...

I'd love to find somebody in the Seattle area with a muffler delete or PE on a 128i that I could get a direct comparison with..But I'm not going to hold my breath. Even if left to my own devices, I'll still eventually get something better and post it up, but possibly not until after opening up a little extra intake noise as well.

Originally Posted by Driven5

Unfortunately, this is all I've been able to come up with so far...

I'd love to find somebody in the Seattle area with a muffler delete or PE on a 128i that I could get a direct comparison with..But I'm not going to hold my breath. Even if left to my own devices, I'll still eventually get something better and post it up, but possibly not until after opening up a little extra intake noise as well.

I'm up north of Seattle in mill creek. I have headers and a PE and I think it's great. Lots of pops and bangs when you want it. But subdued on the highway. Even with my 3.73!gears. Happy for you to come up and have a listen.

[Driven5]

Headers and PE seems like a bit of an unfair comparison, LOL, but that's no reason not to anyway. I'm actually in Kenmore, so not far at all. Let's set something up via PM.

[Nixis]

So you have 135i muffler, resonator, and then no secondary cats? Are you auto or manual? I have the 135i muffler then no resonator with secondary cats and I dont think I'm nearly as loud as your video.

[Driven5]

Correct. The transmission shouldn't matter, but it is a manual. I'm honestly not sure how accurate of a depiction this video is, since I don't have a good frame of reference. Out of curiosity, is your 135i muffler N54 or N55?

[Nixis]

Weird all the exhaust clips I've seen for manual cars always seem to sound louder while comparing same setups. I'm not sure, I got it from another forum member ill see if I can find the old post.

EDIT: It's a n54 muffler, does it matter?

[Driven5]

N54 had a significant amount of additional perforated area inside the muffler compared to the N55, making it quieter. So that could be some of the difference you're detecting as well.

It seems reasonable to me that the cats, muffler, and tubing diameter, could have more combined net effect than the resonator. Especially considering the 135i resonator had only maybe 1" (or less) of perforation in it.

[Nixis]

Wow thanks didnt know that, does your car burble a lot on the decel with the decat as well or does the muffler muffle most of that? Basically all the videos I see on YT that have decat or resonator delete have their muffler deleted too

[Driven5]

It's there on decel above 2k rpm, but possibly softer and more muted though. Think burbles and pops, rather than crackles and bangs.

It also dawned on me today that I should be able to rig my old roll bar camera mount to the tow hook to get a better audio clip posted up.

[Nixis]

you think it would be worth it to cut open the muffler and wrap some of the perforations or just get the secondary cat delete?

[Driven5]

Honestly, I have no idea how much (or little) effect either might have, nor how they would individually compare. Intuitively, without any resonator, I'd have more concern about drone with the muffler mods. The secondary delete is probably the more straight forward job too.

https://www.1addicts.com/forums/show...6&postcount=18

[Driven5]

Sorry about the wind and road noise, but I supposed it's more true to how it sounds with the top down. With the top up what you hear is a bit more subdued.

[munkie]

Originally Posted by Driven5

Sorry about the wind and road noise, but I supposed it's more true to how it sounds with the top down. With the top up what you hear is a bit more subdued.

Do you have your valve/flap activated in the video, or is it plugged up and zip tied?

Sorry to resurrect an old thread...