OEM exhaust mod questions

[Legion5]

So from what I understand there are 4 chambers in the exhaust each with a perforated pipe.

If you just want the exhaust to sound a little louder and a lot better, you replace the perforated pipe with a straight one in the INNER 2 chambers. If you want the exhaust to sound a lot louder, you replace the perforated pipe in all the chambers.

I just want to make sure everything is right.

[M3+]

Originally Posted by Legion5

So from what I understand there are 4 chambers in the exhaust each with a perforated pipe.

If you just want the exhaust to sound a little louder and a lot better, you replace the perforated pipe with a straight one in the INNER 2 chambers. If you want the exhaust to sound a lot louder, you replace the perforated pipe in all the chambers.

I just want to make sure everything is right.

INNER 2 YES . OUTER 2 STRAIGHT & 90s .

[M3+]

Originally Posted by M3+

INNER 2 YES . OUTER 2 STRAIGHT & 90s .

HERE'S THREAD http://www.m3post.com/forums/showthread.php?t=320052

[dilav]

if all perforated sections were replaced with straight pipes... the thing would no longer be a helmholtz chamber... so can just leave out the oem muffler.

[1sikbmr]

Originally Posted by dilav

if all perforated sections were replaced with straight pipes... the thing would no longer be a helmholtz chamber... so can just leave out the oem muffler.

what?

of course there still is. look at the diagram again

[MShift]

I read through the entire original thread last night and I didnt see any videos of what happens when you do what the second diagram shows above. Does anyone have links to one?

[M3+]

Originally Posted by MShift

I read through the entire original thread last night and I didnt see any videos of what happens when you do what the second diagram shows above. Does anyone have links to one?

sounds like DINAN mufflers ''basically same design'' but in oem can & much less $$$

[elp_jc]

Originally Posted by M3+

sounds like DINAN mufflers ''basically same design'' but in oem can & much less $$$

It didn't occur to me until now that what you did is EXACTLY what Dinan mufflers look like indeed . I gave them too much credit for the design . And your car sounds just like those... with real tips and much better fit. Hey, there's no need to reuse the packing material without absorption holes on the pipes. But it'd be nice to have both to 'absorb' the raspiness.

[M3+]

Originally Posted by elp_jc

It didn't occur to me until now that what you did is EXACTLY what Dinan mufflers look like indeed . I gave them too much credit for the design . And your car sounds just like those... with real tips and much better fit. Hey, there's no need to reuse the packing material without absorption holes on the pipes. But it'd be nice to have both to 'absorb' the raspiness.

actually i do have 20 1/4'' holes in the straight pipe from the helmholtz to the Y & all the packing is in it

[MShift]

Thanks for the video. A friend of mine is making a race car M3 and the stock exhaust is off the car. If someone is interested, let me know! Otherwise I'm gonna buy it and have it modded so its ready for when I get my M.