Quick Review of ACM and 4 pipe OEM mod

[pooyab]

I had it done at Exhaust Works in Belmont, Todd is a great guy. If you're in the Bay Area and you want either one, go there.
I ended up going the 4 pipes method and I definitely won't regret it.
The shop gave me a ACM modded one he had while he worked on mine. So I'll give my opinion on both real quick.

As soon as I hit the highway the drone at 80MPH/3k RMP was killing my ears. It sounded great on city streets and the parking garage though.The kids in my neighborhood loved hearing the M drive away too lol. Very deep bass sound, more of a muscle car than euro. Very aggressive, if the M3 is just a weekend car or something then this is your exhaust. Crazy loud revs. Actually echoed in the hills by my friend's house. I'd assume a muffler delete sounds very similar to this because this does completely bypass the chambers as well. You'd need to have a pretty high drone tolerance if you daily this on the highway, or drive at 65MPH.

I picked up mine today and I did some driving but not much WOT. No drone, made me so happy. The chambers and stuffing do their jobs well, definitely suitable for daily driving. In the lower RPM range there is a fair bit of volume loss, but it's still quite loud in the upper, maybe even louder than the ACM, according to my brother. I haven't heard it from the outside myself yet. But i do know it's still much louder than the stock, because the exhaust is still audible around city streets. The sound is definitely cleaner than ACM. Sounds more like a Euro sports car, higher pitched than the ACM and smoother.

Big thanks to M Power-Belgium. He answered any question I had about all three versions and helped me reach my decision.

[Silverwolf]

Interesting review. I too had Todd do my ACM mod and love it for the exhaust note and the affordability but after a few months, I found it to be less interesting on the high rpms and made the swap to Meisterschaft GT2. Have had it for a few months now and i'm still looking for a little more punch which i'm hoping the test pipes will do the trick. I guess, I have a pretty high tolerance as the drone hasn't really been apparent to me thus far on both setups.

[pooyab]

Originally Posted by Silverwolf

Interesting review. I too had Todd do my ACM mod and love it for the exhaust note and the affordability but after a few months, I found it to be less interesting on the high rpms and made the swap to Meisterschaft GT2. Have had it for a few months now and i'm still looking for a little more punch which i'm hoping the test pipes will do the trick. I guess, I have a pretty high tolerance as the drone hasn't really been apparent to me thus far on both setups.

Volume wise I really liked the ACM. I was actually kinda sad it was droning. GT2 with test pipe should be sound crazy. Be in LA and I'll still hear you in the Bay lol.

[Bimmer22]

Originally Posted by pooyab

The sound is definitely cleaner than ACM. Sounds more like a Euro sports car, higher pitched than the ACM and smoother.

Thank's for sharing this. I've been searching hard for a review like yours.....which is practical and 'real' having had the experience to drive both within a close period of time.

Question, regarding the perforated mod do you think there is much of a difference if only 2 pipes are changed out vs. 4?

[Silverwolf]

Yeah I am excited to hear what the final product would sound like. I like the GT2 and hope the test pipes will add to it making it more intoxicating.

[pooyab]

Originally Posted by Bimmer22

Thank's for sharing this. I've been searching hard for a review like yours.....which is practical and 'real' having had the experience to drive both within a close period of time.

Question, regarding the perforated mod do you think there is much of a difference if only 2 pipes are changed out vs. 4?

There's definitely a volume difference. Philippe told me the the 2 pipe method is about 15% louder than stock and the 4 pipe is about 20-30% louder than the 2 pipe. And ACM is even louder than that but losses the cleanness.

[///M Power-Belgium]

Originally Posted by pooyab

I had it done at Exhaust Works in Belmont, Todd is a great guy. If you're in the Bay Area and you want either one, go there.
I ended up going the 4 pipes method and I definitely won't regret it.
The shop gave me a ACM modded one he had while he worked on mine. So I'll give my opinion on both real quick.

As soon as I hit the highway the drone at 80MPH/3k RMP was killing my ears. It sounded great on city streets and the parking garage though.The kids in my neighborhood loved hearing the M drive away too lol. Very deep bass sound, more of a muscle car than euro. Very aggressive, if the M3 is just a weekend car or something then this is your exhaust. Crazy loud revs. Actually echoed in the hills by my friend's house. I'd assume a muffler delete sounds very similar to this because this does completely bypass the chambers as well. You'd need to have a pretty high drone tolerance if you daily this on the highway, or drive at 65MPH.

I picked up mine today and I did some driving but not much WOT. No drone, made me so happy. The chambers and stuffing do their jobs well, definitely suitable for daily driving. In the lower RPM range there is a fair bit of volume loss, but it's still quite loud in the upper, maybe even louder than the ACM, according to my brother. I haven't heard it from the outside myself yet. But i do know it's still much louder than the stock, because the exhaust is still audible around city streets. The sound is definitely cleaner than ACM. Sounds more like a Euro sports car, higher pitched than the ACM and smoother.

Big thanks to M Power-Belgium. He answered any question I had about all three versions and helped me reach my decision.

Perfect review !
BTW....You made the right choise,no doubt ! And it was all my pleasure

[BGR]

Originally Posted by pooyab

I had it done at Exhaust Works in Belmont, Todd is a great guy. If you're in the Bay Area and you want either one, go there.
I ended up going the 4 pipes method and I definitely won't regret it.
The shop gave me a ACM modded one he had while he worked on mine. So I'll give my opinion on both real quick.

As soon as I hit the highway the drone at 80MPH/3k RMP was killing my ears. It sounded great on city streets and the parking garage though.The kids in my neighborhood loved hearing the M drive away too lol. Very deep bass sound, more of a muscle car than euro. Very aggressive, if the M3 is just a weekend car or something then this is your exhaust. Crazy loud revs. Actually echoed in the hills by my friend's house. I'd assume a muffler delete sounds very similar to this because this does completely bypass the chambers as well. You'd need to have a pretty high drone tolerance if you daily this on the highway, or drive at 65MPH.

I picked up mine today and I did some driving but not much WOT. No drone, made me so happy. The chambers and stuffing do their jobs well, definitely suitable for daily driving. In the lower RPM range there is a fair bit of volume loss, but it's still quite loud in the upper, maybe even louder than the ACM, according to my brother. I haven't heard it from the outside myself yet. But i do know it's still much louder than the stock, because the exhaust is still audible around city streets. The sound is definitely cleaner than ACM. Sounds more like a Euro sports car, higher pitched than the ACM and smoother.

Big thanks to M Power-Belgium. He answered any question I had about all three versions and helped me reach my decision.

I’m resurrecting this thread based on a conversation I’ve been having in a FB group.

There was a comment above that “the chambers and stuffing do their jobs well” with the 4 pipe. Looking at pictures, you are completely bypassing that central chamber and stuffing, which is essentially the ACM, just with a couple more bends. Both are still utilizing the helmholz chamber, so both should sound pretty close to the same.

[Powashiftin]

Originally Posted by BGR

I'm resurrecting this thread based on a conversation I've been having in a FB group.

There was a comment above that "the chambers and stuffing do their jobs well" with the 4 pipe. Looking at pictures, you are completely bypassing that central chamber and stuffing, which is essentially the ACM, just with a couple more bends. Both are still utilizing the helmholz chamber, so both should sound pretty close to the same.

Very different exhaust sounds. Regardless of what you read. I had the 4 pipe mod and enjoyed it but since moved on to a corsa with a catless x pipe. Sounds much better IMO.

[BGR]

Originally Posted by Powashiftin

Very different exhaust sounds. Regardless of what you read. I had the 4 pipe mod and enjoyed it but since moved on to a corsa with a catless x pipe. Sounds much better IMO.

So I’m assuming you also had the ACM? Otherwise, how can you claim very different sound...

[Powashiftin]

Originally Posted by BGR

So I'm assuming you also had the ACM? Otherwise, how can you claim very different sound...

No. One doesn't have to own an exhaust to compare... find someone locally with the ACM mod to their muffler and listen for yourself.