ACM OEM Exhaust Mod

[W///]

Originally Posted by PicassoM

OK UPDATE.

So I took her for a long drive yesterday and really payed attention to the sound up at the higher speeds. Around 80mph, in order to consistently cruise at that speed you have to have a little bit of gas and the RPM will be around 3k. Well there is a slight drone around 80mph, good news... it's really not that bad. Certainly not deafening or really loud. But you do hear a rumble. It's aftermarket and def louder so I guess that's one thing you have to take with a grain of salt.





Thanks John! Good luck with the install, it will def be louder than it was!



Personally I don't understand the point in coating the muffler, can anyone explain?

Because the stock cans stick way past the bumper and look ugly. At least painting it black hides it better. I'm definitely going to do that when I do ,y exhaust

[tibra1]

It looks better..especially on an AW car those silver cans are gross

[FLOSS M]

Just had the ACM mod done today, sounds great! The guys at ACM are very cool. No Drone

[dinkman]

out of curiosity, how much did the oem job at ACM cost? thanks

[FLOSS M]

leaving your old muffler, $400 plus 1HR labor ($100) and tax.

[dinkman]

i just got the same mod done today.
30 mins and $530 including labor and tax and you're in heaven.

OP, thanks for posting this!

[NYC Drifter]

Having a good visit with the great guys and Brutus (puppy) at ACM as they are track preping my car with brake fluid and Hawk pads. The OEM exhaust mod is going on. All black can and tips. Pics later. Can't wait for the test pipes to be ready

[Lalit@autocouture]

Thanks for the review Jared! PM me any questions that you guys may have.

[NYC Drifter]

I ran Summit Point this past weekend with the BMWCCA NJ chapter. Great time!

Wish that I had vid though because the exhaust received alot of compliments especially at full tilt down the front straight.

[NYC Drifter]

Originally Posted by m3alabama

test pipes with this will be insanely loud just so you know

Yes it will be very loud and raspy Bama. ACM is working on a bolt on primary delete which with a tune should give 40 HP pre-wheel? I'm in.

[m3an]

better alternative= muffler delete pipes.

It is the same thing, and I have done em myself, looks much better, you can run any tips you want, and you save a lot of weight

[ThatGuyMikee]

^^ any piks of how you did it?

deciding if i shiuld cut the oem muffler and do the od or just delete the whole muffler and do delete pipes

[m3an]

Originally Posted by ThatGuyMikee

^^ any piks of how you did it?

deciding if i shiuld cut the oem muffler and do the od or just delete the whole muffler and do delete pipes

just look under the car. Cut the pipes right as they enter the muffler and you will then just need 2 straight sections. Any competent muffler shop can do it in no time. It really does sound great. The e39 m4 guys have been doing it forever so I figured it would sound great. I have a video somewhere.

As for the sound::

I switch back and forth sometimes from my gintani race. It's more throatier than the gintani, but the Gintani drones like crazy and amazingly the straight pipes don't. It's def loud, but the sound is behind the car and not beating you inside of it.

[m3an]

Also you can always just cut it again and weld the stock muffler back on without having the muffler internals all hacked up. And to be honest it is like a $250 job TOPS. The prices people are paying to modify the stock muffler is silly IMO.

[ThatGuyMikee]

^^ thank you!

[nmehta211]

i'm curious what the sound db is at full throttle. I am running at Lime Rock tomorrow and they have an 87db limit. Hope i make it with this mod!

[IbanezGod]

No clue what the db is... but it's not super quiet. I'd say if you did a straight pipe cat delete it would be too loud.

[bretster]

Originally Posted by PicassoM

No clue what the db is... but it's not super quiet. I'd say if you did a straight pipe cat delete it would be too loud.

+1 What Jared said.

It's not too loud, there's no such thing as too loud. It's just really really loud from the outside and suprisingly quiet from the inside.

[W///]

Did this mod about 2 weeks ago. Haven't had a chance to drive my car that long with the exhaust but it's not for the faint of heart. At idle, you can tell something has been done. It is considerably louder than stock at any RPM range, haven't had a chance to go WOT yet. If you manage your RPM's (aka keep them under 2k), you can get around town quietly. When I'm driving normally, I'm between 2-4k anyway so it's not too bad.

There is drone though, no doubt about that. Not all conditions of course, but it's there, which is expected. For example, fourth gear, going up a hill, there's enough resonance to make some clips rattle in the headliner rattle too.

Going muffler delete is probably the easiest route but:
- I think it'll be louder than this mod, which is about as loud as I want to go (yes there is something as too loud)
- This is just a theory but I think the chamber in the middle still absorbs SOME sound and drone. Just my guess.

[MTrezzz]

Ive been running a "expensive ACM muffler mod" (Eisenmann black series RACE full), just wanted to know if any switched from a high end mod to something like a cut and weld.
OEM ACM Mod.

[W///]

Originally Posted by MTrezzz

Ive been running a "expensive ACM muffler mod" (Eisenmann black series RACE full), just wanted to know if any switched from a high end mod to something like a cut and weld.
OEM ACM Mod.

Like I said in other thread, if you are doing muffler only, ACM is fantastic. But if you want to go test pipes/catless version later, I'd keep Eisenmann Race for sure.

[IbanezGod]

Originally Posted by MTrezzz

Ive been running a "expensive ACM muffler mod" (Eisenmann black series RACE full), just wanted to know if any switched from a high end mod to something like a cut and weld.
OEM ACM Mod.

depends what you want. The ACM doesn't add power or flow. Just lets the true sound out. That's all I wanted as my mod cost $500 out the door vs. $4000+ for Eisenmann