ChevyZ76

Had a few things all done at once. Speed Engineering 1 3/4" headers with the SE ORY, a Yank SS3600 stall. And poly motor and trans mounts. And a tune up with NGK platinum plugs and MSD wires. Had the computer tuned by frost. When letting off the gas I get a bad rattle underneath the car, such as the exhaust hitting the floor of the car. I know I have some exhaust leaks cause the clams that came with the headers did not seal correctly.

Today i installed my strut mount brace thinking that might tighten up the front. And maybe keep it from shaking. But if anything the banging is worse. Although the front of the car feels nice and tight.

Car runs great, besides this banging noise

Any ideas? Anybody else have these issues? If so how did you rectify the problem?

Thanks guys

PS- It gets worse when the AC compressor is on. So I am pretty sure the issue is a vibration in the motor

MYSTIC-1SC

iTrader: (14)

Sounds like its probably exhaust clearance related. Just may need to get underneath it and do some adjusting.

Jtm2085

iTrader: (1)

Sounds like the y pipe is banging your floor board...

omarrakeen

iTrader: (2)

i had this issue too but poly motor mounts solved it. i bet its the Y pipe not the headers. i would wedge a thick rubber between Y pipe and floor and go for a ride, if banging stopped then your Y pipe is too close. its annoying af i know..

98CayenneT/A

This is where I would start also, it also would not hurt to crawl under there and double check a couple bell housing bolts, tranny mount bolt, tranny cross member bolts and torque arm bolts if wedging something in-between the exhaust and floor board does not help

BandDirector Blk98ZM6

iTrader: (21)

...it's been a while, but I seem to remember a sponsor carrying a product that clamps to the Y-pipe and then has a tension spring that goes up against the floorboard to keep it from banging...I have NO idea who carried it though...

Cajun ELESS-ONE

i had the same issue. it was the ypipe and the clamps that camw with the kit. i got the lap joint band clamps. wrapped the joints in header wrap then clamped it down. it tightened up the exhaust alot and i have no more leaks. id go that route with the leaks issue. id bet its the ypipe banging on that part under the driver seat and or where the headers bend by the wheel well. id take a hammer to that area. had to do it on mine and my friends car