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DISCUSSION => Engine + Driveline => Topic started by: harvey2 on February 07, 2010, 02:26:55 AM

Title: Exhaust intensity
Post by: harvey2 on February 07, 2010, 02:26:55 AM

I've just had a new muffler put on my '91 318is and its too loud.  So I'm wondering what the next step is.

Heres' the lineup:  stock header, free flow cat, (resonator deleted), 2.5 inch pipe back to Magnaflow (4x9oval free flow universal fit) muffler, 2.5tailpipe.

The deep tone at low revs is nice, but overall this system is just too intense and breaks the sound level limit at autocross especially at higher revs.  I need to take out at least 4 dB.

Should I put a resonator back in?  Or resonator and a different muffler?

Title: Exhaust intensity
Post by: BlueBMW on February 07, 2010, 08:52:08 AM

Monday I'm re-doing my exhaust.  Currently it is this...

No cat... some resonator in the middle.... then a fart can in the back...

Loud but more bothersome, its obnoxious!

My intended setup is....

Universal cat... keep the existing midpipe resonator.. and then a dynomax super turbo muffler in the back.   I'll let you know how it sounds when its done.

Title: Exhaust intensity
Post by: flyinglizard on February 07, 2010, 11:34:27 AM

You need a box of some kind before the muffler. A  Cherry bomb works fine in the trans tunnel.  With out it the noise has a Honda Like rasp to it.
  With it, it  takes the hard sound out of it.IMHO. MM

Title: Exhaust intensity
Post by: dvmotorsports on February 07, 2010, 05:05:07 PM

Just toss a resonator inline.

Title: Exhaust intensity
Post by: 4banger on February 07, 2010, 05:09:01 PM

glasspacks make a good resonator. ive got a 15in stainless one from jegs in mine. mines still raspy between 2500-5k but i atribute that to the 2.5in 1 chamber flowmaster thats on it haha. it needed to be inspected and all i had in the shop was the flowmaster. its getting a 40 series 2 or 3 chamber soon tho.

Title: Exhaust intensity
Post by: harvey2 on February 07, 2010, 08:05:00 PM

Thanks for the advice.  As everyone is suggesting, I'll put in a resonator of some sort, maybe 12 inch or a bit bigger, whatever seems like a decent fit.  I'll try that for a while and if it isn't enough, then I'll bite the bullet and change the muffler to something bigger.

Title: Exhaust intensity
Post by: Rich86 on February 08, 2010, 01:26:28 PM

I had stock header to cat delete, then a small resonator to a 2 1/2" cat back into a magnaflow oval. Was a nice volume with a bit of rasp in the mid rpm range. After I put the cat back in it was much better for everyday driving. Nice deep tone, but no rasp, and no longer attracted ricers.

Title: Exhaust intensity
Post by: harvey2 on February 08, 2010, 03:36:30 PM

Ok, we installed a 12 inch glasspack type resonator just behind the free-flow cat that was already in there and I think it is good now.  Overall, the intensity is toned down noticeably, especially at high revs, but we didn't lose that really nice Magnaflow deep burble at low revs.  There was a bit of midrange rasp which has been eliminated too.  I don't notice any difference in power or willingness to rev.  I must say, I'm now a big fan of that Magnaflow sound, its got some meat to it.

Title: Exhaust intensity
Post by: BlueBMW on February 10, 2010, 08:47:31 PM

I finally got my exhaust installed today.  Came out perfect!  Installed the magnaflow universal cat in front of the existing resonator and replaced the fart box with the dynomax super turbo muffler.  Nice and quiet at low rpms, throaty sound all the way up, not too loud, but not too quiet.  Most importantly though, no more honda ricer raspy noise.  It sounds almost exactly like the sound clip over at r3vlimited.com  Oh and the nasty burnt smell from not having a cat is gone too!

http://www.r3vlimited.com/media/M42Dynamax-clip1.mp3