HMS rear exhaust review & HMS midpipe review; EDIT: Dyno Charts added

[Piets94]

(Edit: the HMS midpipe review is later in the thread).
(Trackday video added later in thread from interior of car).

So... I finally made my first mod to this awesome car after 12 months of ownership, and couldn't think of a better place to start than the exhaust.

The HMS exhaust was my choice, principally because I thought it sounded amazing on some YT clips, but also because it wasn't too common (like Eisenmann, Akrapovic, etc). Whilst some pictures and info is out there, there doesn't appear to be a comprehensive review of the HMS exhaust for the 1M by an owner. Hence, I thought I would write a review of my impressions of this cat-back exhaust option, list some pros/cons, upload some pretty pictures, and hopefully (in the near future) upload some videos of the exhaust in action.

**I will largely refrain from comparing this exhaust to others out there, simply because I have not heard any of the other brands in person, and You Tube clips seem only as good as the camera recording**

Firstly some technical specs:
Construction - stainless steel 76mm
Weight - ~1/3 lighter than stock
Tips - silver chrome or black chrome, 90mm diameter x4, bevelled and rolled
2-setting wired flap-control to modulate sound
Power - no claims made on increases, (but to be determined soon by myself)

Observations:
Customer Service - great. Informative, prompt
Price - expensive, about 5k Australian (made, shipped, installed), although not as expensive as Ti Akra.
Quality/finish - pretty much spot-on for an exhaust of this price and calibre. I opted to have the 'M' logo on the tips, which is additional cost. The exhaust is made to order in Germany. Logo can be custom, absent, or HMS.
Aesthetics - similar to stock, but tips are larger and more aggressive, just how I wanted it.
Installation - the physical fitment of the exhaust was relatively simple, although some maneuvering was required to line the tips up perfectly with the diffuser. Also, the spring bolts joining the rear exhaust to the mids needed to have the springs cut short a little to allow complete tightening as the exhaust flange was a solid thickness (and not identical to the stock flange).
Wired valve-control - the exhaust flaps are controlled by a wired button, and installed anywhere within the car interior. The installers opted for a location just near the OBD port for maximum stealth from law enforcement! Glows 'red' when in 'attack' mode. Apparently a bit of pain to install, but this could be as simple or as difficult as you make it. The installers opted for max discretion (and max difficulty), so ran the wiring beneath the interior trim. This required the rear seats out, but the result is no visible modification to the car. Alternatively, the wiring could be run below the car, which would make this part of the install much easier.

Finally...the sound:

If there are any 1M owners that have a stock exhaust and are debating about whether to change it or not, DO IT. There is so much to be gained as far as aural excitement with a nice sounding exhaust on this car. I feel that the HMS cat-back is an amazing option.
Stealth Mode
When in stealth mode, I would have to say that the exhaust is possibly a little quieter than stock, perfect for cross-country commuting. AND, drone is definitely reduced to my ears (although the 'drone' that so many complain about with the stock exhaust has never bothered me). What would have been the icing on this cake is for the stealth mode to sound more similar to stock - which is an overall nice sound.
Attack Mode - almost all the time for me
So many adjectives to describe the sound - deep, masculine, rumbling, popping, barking, thumping, a real thunderclap. This car always made me giggle before, now it just scares pedestrians and sometimes even myself with the sound. There is fantastic character at all parts of the rev range, and it doesn't sound like a truck at idle like a few other exhausts out there. The car definitely feels a little punchier, but that could just be the sound talking.

I'll finish by saying that I LOVE it. If your exhaust budget can stretch to it, definitely shop the HMS against the other brands. I am now looking forward to changing out the mids soon for some more power and sound.

Will hopefully post some vids soon.

Cheers

P.S. The wife still hasn't picked it - thankyou stealth mode!

[css008]

Awesome!! You can tell the tips are larger than stock and look great w/ the M Logo. My exhaust just came in, and it's my first mod as well. Would love to hear some audio

[CyRaX]

Could you post a pic which shows the tips straight from behind?

[Piets94]

Originally Posted by CyRaX

Could you post a pic which shows the tips straight from behind?

I'll try to get that photo up soon. Just posted a cold-start YT clip under HMS flap-exhaust (threepeat), although nothing too exciting yet. Some warm engine vids to come!

[ozinaldo]

Thank you for this great review for what I was considering a great exhaust since some time

If I stay with the 1M long enough to pass to a second exhaust after Evolve+N55 mids one day, this one is at the very top of my list for exact same reasons you listed.

[Artemis]

OT: I thought that no 1M was equipped with a boot opener (at least EURO spec didn't get it). How come ? Did BMW make an exception for Australia ?

[Piets94]

Originally Posted by Artemis

OT: I thought that no 1M was equipped with a boot opener (at least EURO spec didn't get it). How come ? Did BMW make an exception for Australia ?

Attachment 941126

Artemis, as far as I'm aware, this is a standard feature in the Australian market. Same as for my previous 135. All OZ 1M came fully-specced to justify the price increase over the 135. Options were limited to I think only 5 or 6? (Paint, CA, high-beam assist, sun glaze, ski racks, mobile connectivity), and most owners specced it right out (although not the ski racks for our pathetic excuse for snow! )

[Piets94]

Just added a short YT clip of some standstill revving for those interested. It's under '1M coupe hms' (threepeat).

[Smiley1175]

Hey mate,

There must have been a rush on HMS orders to OZ. I just had mine fitted a few weeks back, yet to get around making a sound clip of it, and I know there's another one about to be fitted to a car in Sydney.
I love how you've got the M logo on the tips, wish I knew about that option!
What rpm is your auto valve opening set to? Mine is 5k, which is way too high and eventually will get around to having this changed, but like you, I have the valve open most of the time. Love the sound!

[Harlequin]

Embedded for you:

[Piets94]

Originally Posted by Smiley1175

What rpm is your auto valve opening set to? Mine is 5k, which is way too high and eventually will get around to having this changed, but like you, I have the valve open most of the time. Love the sound!

I had the auto valve-opening set at 4400 rpm at HMS' recommendation, but I don't reckon I can tell when it opens! I've tried to listen hard, but the time spent above 4400 on public roads is over pretty quickly, so it might not be easy to hear it open and close. Not that it matters much, as I think you either feel like some peace and quiet OR some noise.

Thanks Harlequin for embedding the clip . Not sure how to do that yet.

[hongounan]

Originally Posted by Piets94

So... I finally made my first mod to this awesome car after 12 months of ownership, and couldn't think of a better place to start than the exhaust.

The HMS exhaust was my choice, principally because I thought it sounded amazing on some YT clips, but also because it wasn't too common (like Eisenmann, Akrapovic, etc). Whilst some pictures and info is out there, there doesn't appear to be a comprehensive review of the HMS exhaust for the 1M by an owner. Hence, I thought I would write a review of my impressions of this cat-back exhaust option, list some pros/cons, upload some pretty pictures, and hopefully (in the near future) upload some videos of the exhaust in action.

**I will largely refrain from comparing this exhaust to others out there, simply because I have not heard any of the other brands in person, and You Tube clips seem only as good as the camera recording**

Firstly some technical specs:
Construction - stainless steel 76mm
Weight - ~1/3 lighter than stock
Tips - silver chrome or black chrome, 90mm diameter x4, bevelled and rolled
2-setting wired flap-control to modulate sound
Power - no claims made on increases, (but to be determined soon by myself)

Observations:
Customer Service - great. Informative, prompt
Price - expensive, about 5k Australian (made, shipped, installed), although not as expensive as Ti Akra.
Quality/finish - pretty much spot-on for an exhaust of this price and calibre. I opted to have the 'M' logo on the tips, which is additional cost. The exhaust is made to order in Germany. Logo can be custom, absent, or HMS.
Aesthetics - similar to stock, but tips are larger and more aggressive, just how I wanted it.
Installation - the physical fitment of the exhaust was relatively simple, although some maneuvering was required to line the tips up perfectly with the diffuser. Also, the spring bolts joining the rear exhaust to the mids needed to have the springs cut short a little to allow complete tightening as the exhaust flange was a solid thickness (and not identical to the stock flange).
Wired valve-control - the exhaust flaps are controlled by a wired button, and installed anywhere within the car interior. The installers opted for a location just near the OBD port for maximum stealth from law enforcement! Glows 'red' when in 'attack' mode. Apparently a bit of pain to install, but this could be as simple or as difficult as you make it. The installers opted for max discretion (and max difficulty), so ran the wiring beneath the interior trim. This required the rear seats out, but the result is no visible modification to the car. Alternatively, the wiring could be run below the car, which would make this part of the install much easier.

Finally...the sound:

If there are any 1M owners that have a stock exhaust and are debating about whether to change it or not, DO IT. There is so much to be gained as far as aural excitement with a nice sounding exhaust on this car. I feel that the HMS cat-back is an amazing option.
Stealth Mode
When in stealth mode, I would have to say that the exhaust is possibly a little quieter than stock, perfect for cross-country commuting. AND, drone is definitely reduced to my ears (although the 'drone' that so many complain about with the stock exhaust has never bothered me). What would have been the icing on this cake is for the stealth mode to sound more similar to stock - which is an overall nice sound.
Attack Mode - almost all the time for me
So many adjectives to describe the sound - deep, masculine, rumbling, popping, barking, thumping, a real thunderclap. This car always made me giggle before, now it just scares pedestrians and sometimes even myself with the sound. There is fantastic character at all parts of the rev range, and it doesn't sound like a truck at idle like a few other exhausts out there. The car definitely feels a little punchier, but that could just be the sound talking.

I'll finish by saying that I LOVE it. If your exhaust budget can stretch to it, definitely shop the HMS against the other brands. I am now looking forward to changing out the mids soon for some more power and sound.

Will hopefully post some vids soon.

Cheers

P.S. The wife still hasn't picked it - thankyou stealth mode!

I'm also considering to have mine changed to HMS, the sound clip on YT is sooo breath taking.
Can I ask any other modification to the power train that you have done to your M? I don't want to touch the ECU at the moment and is choosing between the Cat-back vs. mids+muffler.

any advice?

Cheers

[Piets94]

Originally Posted by hongounan

I'm also considering to have mine changed to HMS, the sound clip on YT is sooo breath taking.
Can I ask any other modification to the power train that you have done to your M? I don't want to touch the ECU at the moment and is choosing between the Cat-back vs. mids+muffler.

any advice?

Cheers

My engine is stock (for now). The vid clip is of the cat-back only. The official HMS 1M video is mid + rear. My mids are to be installed soon. The mids give a slight power increase and make the system louder by about 10-15%, but might drone as there is no resonator like on n55 mids. Depends what you're after

[hongounan]

Originally Posted by Piets94

My engine is stock (for now). The vid clip is of the cat-back only. The official HMS 1M video is mid + rear. My mids are to be installed soon. The mids give a slight power increase and make the system louder by about 10-15%, but might drone as there is no resonator like on n55 mids. Depends what you're after

Thanks mate!
I'll probably try the cat-back first as you have, and see if I need the cat to be removed.
looking forward to see your review on the system with mid pipe.

one more thing about the auto-valve open thing, is that really working well? i couldn'd recognize it from the vids, and do you think it could be a good idea to set the rav at 3000rpm for the auto-valve?

[Piets94]

Originally Posted by hongounan

Thanks mate!
I'll probably try the cat-back first as you have, and see if I need the cat to be removed.
looking forward to see your review on the system with mid pipe.

one more thing about the auto-valve open thing, is that really working well? i couldn'd recognize it from the vids, and do you think it could be a good idea to set the rav at 3000rpm for the auto-valve?

I haven't connected the wiring for the auto-opening of the valve yet, so you won't be able to hear it on the vid. I'm not so sure you really need it as you either want loud or quiet. HMS recommendation is 4400, 3k seems a little low and I reckon it will get annoying with constant open/close. I'm driving 90% valve-open anyway

[hongounan]

Originally Posted by Piets94

I haven't connected the wiring for the auto-opening of the valve yet, so you won't be able to hear it on the vid. I'm not so sure you really need it as you either want loud or quiet. HMS recommendation is 4400, 3k seems a little low and I reckon it will get annoying with constant open/close. I'm driving 90% valve-open anyway

ok got it. thanks

[Piets94]

Originally Posted by Ian///M

What was the landed cost in AUD?

Why did you put the valve button so far out of reach?

Cost was about 5k AUD for the rear exhaust. The button isn't really so far out of reach. A simple lean forward is sufficient. Several reasons though: discreet (so cops can't see it); ease of installation (it's wired in, not wireless, and to get access to the centre tunnel would have been too difficult); and the part it's installed on is a cheap plastic bit so that if for some reason you wanted to revert to stock, the plastic can be replaced.

[ALEJANDRO]

HMS sounds definitely better than Akra, more refined, yet aggressive in my opinion..., I'm just not into the tips particularly, (nor the akra ones…). wish these look like the akra ti tips for the M3

[ALEJANDRO]

My observation about the HMS sound is based on previous clipping I've heard. there's one in the internet which is truly amazing.

http://www.youtube.com/watch?feature...&v=-dRbEUToTDY

I think the HMS is not so expensive in the US. it is around 3.something K

still very expensive. so there must be something special about this company considering they don't use ti but steel..

[Piets94]

Originally Posted by Ian///M

The finish of the HMS doesn't look to be on par with the Akra or Lightweight units IMO.

I beg to differ Ian. I'm not sure of the manufacturing/finishing processes of any of the major brands, but I would hesitate to compare stainless steel with titanium. Akra finish is hard to fault, but you would expect that from the price you pay, and titanium may have different properties that allow the units to be finished in a particular way...I don't know.

All I can say is that the HMS is extremely well made for a traditional steel exhaust. It's expensive compared to say an Eisenmann, but you are getting a wired flap-design system that can play rough and nice, similar to the Akra unit. Price in US is about 4k, in Australia is 4.3k (but we have to pay tax and duty on top if this).

AND, it doesn't sound like a truck at idle (Akra) and your nice steel won't change colour over time like titanium - the chief reasons I didn't go Akra.

Both sound awesome, just in different ways.

[ZA_1M]

Originally Posted by Artemis

OT: I thought that no 1M was equipped with a boot opener (at least EURO spec didn't get it). How come ? Did BMW make an exception for Australia ?

Attachment 941126

The South African version has the boot opener as well

[hongounan]

Originally Posted by ZA_1M

The South African version has the boot opener as well

I wonder if it's after-marketable...