Mossad

Hey guys,

I just finished installing my Mugen exhaust, and everything went fine. When I took the car out for a test drive however, I noticed a slight vibration/twanging happening at 2,500, 4,000, and 4,750RPM during acceleration and decel. It's tough to pinpoint the source of the noise, but it seems to be coming from the rear of the car.

Does anyone have any pointers? Similar experiences?

Any help would be appreciated. Thanks.

kevieeroh

i remember when i installed exhaust on my civic it rattled and i took it back to the place and they jus adjusted something and never heard it again..
goodluck Amir!

BocaS2000

I'd suggest getting under the car and moving the exhaust around a bit and see if it comes close to hitting anything (ie. frame, heat shield, bumper). While the car is at the rpm you stated, it could be vibrating the exhaust against something. I had a similar problem and I found the exhaust was hitting on the side of the bumper. When installed, the exhaust came close, but cleared the bumper. Under mid-range rpm, it slightly rattled against the bumper. Talk about annoying. The fix was to adjust the hangers.

Also, I presume that the exhaust was installed properly and torqued to spec. If a shop did it, take it back. I'm sure xviper would be able to offer some good insight for you.

xviper

It's quite odd that you have 3 distinct resonance points for this vibration and it's also odd that you get it when both in accel and decel mode. What's even more remarkable is that you are able to pinpoint it so accurately to such precise rpms.
Most exhaust movement is when accelerating under load. It is during this time that you will see the most vibration at the exhaust tip if you were to view the rear of the car while following. This can be contributed by rubber hangers that are either getting too old, cracked, or not used (or missing). Did you use all the proper hangers?
Also, the fact that you get this noise on accel and decel may be an indication that something could be rattling around inside the system. I'm wondering if something came loose or broke off on the inside during shipping and handling or perhaps some solid debris found its way into the piping during the time between the packing and the time you received it. If this is the case, you should be able to go under the car and give good solid thumps all along the system to see if something can be "bounced" around.

Road Rage

My Mugen is dead slient mechanically, hot or cold, even after being ignored for weeks at a time. I think either a hanger is installed wrong, or perhaps part of the heat shielding is rubbing. As xviper indicated, multiple resnant points are not indicative of an exhaust resonance per se.