Performance exhaust vs OEM Mod

[08whtx5]

Has anyone done a sound comparison between the two?

[Superfly_M3]

yes they have, search for it.

[kthxbye]

I've heard both in person and they sound 97% identical to me. The slight difference is due to the type of metal used. I DJed for 10 years and have very sensitive ears and could only tell a slight difference side by side. If they weren't side by side I wouldn't even be able to tell that side by side.

I posted in another thread earlier today, but over the weekend I discussed my Auto Couture Motoring exhaust mod with a BMW representative/enthusiast (who is on the forum, but wishes to remain unnamed for obvious reasons) and he assured me that design wise the ACM mod is identical to the M Performance Exhaust. The M-Perf uses a slightly lighter material, but for the $3000 difference I can live with a few extra pounds - the ACM mod doesn't weigh any more than stock

[kthxbye]

There are a few different schools of thought on what exactly the OEM mod entails, I would review the few options available - you'll find them all on the forum.

My experience has only been with the ACM method

[Da M3nace]

Im all eyes. Really interested on this topic. Videos are not reliable.

[immiketoo]

The big difference is $$$

[kmarei]

Originally Posted by immiketoo

The big difference is $$$

and the associated weight loss from your wallet
might help your lap times

[jeff@autocouture]

http://www.m3post.com/forums/showthr...1#post11521969
check out our official thread, videos are good, sounds better in person though!

[Ablahad]

How does the exhaust mod affect warranty claims and whatnot? You can't return a leased vehicle with the mod can you?

[kmarei]

Originally Posted by Ablahad

How does the exhaust mod affect warranty claims and whatnot? You can't return a leased vehicle with the mod can you?

exhaust mod if done corectly (meaning the box is cut from the top)can't be detected. Unless the dealer removes the entire exhaust andlooks at the top of the muffler
that's assuming you do the old style not the ACM style
i've heard both mods
original mod sounds stock at idle, only sounds loud after about 3000rpm
ACM mode sounds loud at all rpm and will be easily noticed and drones big time

[Ablahad]

I appreciate the information.

[serranot]

I did the "old style." It's perfect for my requirements--no drone, and not sound stupid loud all the time.

[jeff@autocouture]

Originally Posted by kmarei

exhaust mod if done corectly (meaning the box is cut from the top)can't be detected. Unless the dealer removes the entire exhaust andlooks at the top of the muffler
that's assuming you do the old style not the ACM style
i've heard both mods
original mod sounds stock at idle, only sounds loud after about 3000rpm
ACM mode sounds loud at all rpm and will be easily noticed and drones big time

we weld it from the top so you dont notice if its on a lift,
what drone are you referring to, ours doesnt drone?? have you heard it in person

[kmarei]

Originally Posted by serranot

I did the "old style." It's perfect for my requirements--no drone, and not sound stupid loud all the time.

agreed
acm style is stupid loud

[kmarei]

Originally Posted by Alex@AUTOcouture

we weld it from the top so you dont notice if its on a lift,
what drone are you referring to, ours doesnt drone?? have you heard it in person

yes i have
i heard both the original mod and the acm mod
2 cars, right next to each other
one had a very noticable drone (ACM)
one didn't(original mod)
and the owner of the ACM mod car said the same thing
on the highway the drone is very obvious, past 3000rpm

how can you not have drone on what is essentially straight pipe?
the acm style doesn't pass through the muffler box at all

[tibra1]

Originally Posted by kmarei

i've heard both mods
original mod sounds stock at idle, only sounds loud after about 3000rpm
ACM mode sounds loud at all rpm and will be easily noticed and drones big time

+1..went with the original mod of removing only the large perf pipes..left the small pipe uncapped..easier to do..no drone..imo its more civil ..the straight pipe method is waaay loud.

[kmarei]

thing is i like loud just as much as the next guy
but when you are on the highway, doing 60-70 for 20-30 minutes on your way from or to work.
and in the backgroud there is a voooooooooooooooooooooooom sound
is gets on your nerves and its annoying to you and the passengers
but if you are at a parking lot showing off to your friends on how loud it is then sure loud is good

[tibra1]

^ Or better still trying to have a conversation with someone in the cabin

[ksflatlander]

I just did this mod yesterday myself. Cut from top and tig welded it back shut. No way to tell unless you pull the muffler back off and even then if you do it right and dont have another one to compare to, you wouldn't know. (I didn't "bubble gum" it all up with a mig welder ).

All the reports are dead on. Either cover or replace the long section of perforated pipe and leave the short section alone, leaving the steel wool.

Car sounds normal at idle. Tone is the same at higher Rpms, just more volume.

[Raptor251]

All I can say is the original version of the exhaust mod, with all the pipes covered, was really quiet. I hardly noticed it at all and was really bummed. I would think the ACM would be perfect, similar to the M performance or Dinan in sound levels. I think ACM also keeps the hemboltz chambers intact so between that and the cats/resonators it should be civil.

[Prince_of_Persia]

Originally Posted by ksflatlander

I just did this mod yesterday myself. Cut from top and tig welded it back shut. No way to tell unless you pull the muffler back off and even then if you do it right and dont have another one to compare to, you wouldn't know. (I didn't "bubble gum" it all up with a mig welder ).

All the reports are dead on. Either cover or replace the long section of perforated pipe and leave the short section alone, leaving the steel wool.

Car sounds normal at idle. Tone is the same at higher Rpms, just more volume.

I did it this way too, around 50% louder than stock.

[dagolfpro]

Originally Posted by Alex@AUTOcouture

we weld it from the top so you dont notice if its on a lift,
what drone are you referring to, ours doesnt drone?? have you heard it in person

I think each individual's own definition of "drones" is different. I did the ACM method and have had various friends in my car and everyone one of them says it's much louder and can hear the exhaust but none have said it "drones".

I was told and from what I've read online, that "drone" means vibrations. Can anyone elaborate on this?