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      07-23-2008, 10:45 PM   #2
First Lieutenant
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New Zealand

Drives: 2008 BMW E90 M3
Join Date: Sep 2007
Location: New Zealand

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Originally Posted by dchen2 View Post

I recently installed the less aggressive single muffler borla exhaust onto my 08 335xi coupe auto and now my car is droning really badly along with a metallic vibration that happens in a certain rev speed..

The exhaust sounds extremely bassy idling and strangely from ~1500-2100rpm is very loud in a low bass tone sort of way but above 2200rpm quiets down and though somewhat louder than my stocks the borla sounds fabulous.

The problem is that since my local highways speed limits are mostly 55, I cruise ~60-65 which is right around 1900-2000rpm and around those speeds the droning is so loud it almost drowns out my music. Also right around 1800-2000rpm there is a weird vibration sound that sounds like either my rear console or part of the exhaust in the rear vibrating that is quite annoying.

I had the muffler shop check for possible exhaust leaks and if parts of the piping might be vibrating but couldn't figure anything out.

During the recent Madison E90 meet earlier this week I checked out a couple other peep's cars and one member who had a Remius quad exhaust with midpipe secondary cat deletes in a 6sp 335i coupe was not nearly as loud idling and he had no drone when cruising.

I am pretty unpleasantly surprised since I heard the single muffler borla was supposed to be virtually drone free due to the built in crossover.

Anyone know what the problem may be and any possible solutions?

I am at the point of just wanting to restore of car exhaust back to stock due to the nearly intolerable droning. Other than the droning and really loud 1500-2000rpm range I really love the sound of the borla though!

I had the same issue with my Remus.

Turned out that my number plate (US translation:license plate) was mounted really badly and was amplifying the sound through the boot lid (US translation:trunk lid)

I spent an hour taking the plate off and covering the back of it with felt tape and re-mounting it.

Drone almost eliminated. Good enough for me!
2008 BMW e90 M3 6MT

1990 BMW e30 325i 5MT