throttlejunkie1

iTrader: (10)

I just had the SLP LM1 removed on my 98. Installed a Magnaflow set up w/ 3" Y-pipe, no cats, 3" I pipe, and back to the muffler. I've been having a vibration at just under 2000rpms and goes away and comes back at 3000 rpms. Took it back to the shop, put it on the lift, and found nothing out of the ordinary. This vibration will also happen in park, reving the motor. I can actually stop and hold it at 3000rpm's for a few seconds and it does this the whole time. I had help running the throttle while I looked under the car and STILL didn't see anything. Open to opinions.

Its not a metal to metal sound either

pewter2002

iTrader: (4)

Check at the over axle section or where the trans brace is?

throttlejunkie1

iTrader: (10)

We checked those two places specifically but the clearance was there and the t-brace was good. A friend of mine told me it might be a harmonic resonation, but I had the SLP LM1 on there before and that is almost as loud as it gets and never did this.

I'm thinking it might be the to rear hangers. I kept the old ones that looked way more heavy duty than the new ones they put on. The new ones have smaller rubber blocks thats bolted to the frame, but the old hangers had like a floating rubber grommet within a metal bracket. Would seem to me that would have more play for movement/vibrations.

pewter2002

iTrader: (4)

AFAIK, mine is dead quiet, no rattles or vibration whatsoever. Maybe it is your headers or y pipe and the LM1 was so loud and with some inherent resonance that you hear it now with a quieter setup? Just guessing at this point. Is the new system *new*? If it is used maybe a baffle in the muffler is broken/loose? Try shaking the muffler?

rabbit320

iTrader: (11)

i usually crawl underneath and bang my fist on it all over. rolling up a piece of paper and holding it to your ear can help isolate sounds. usually just some extra tightening of clamps is needed, or did something else get loosened on install?