2.5" dp + 3" c/b = Really bad Flutter at 3.5k rpms

[95TSiNewbie]

Awhile back I posted this problem before but got no replys. I installed a 2.5" down pipe with a 3" Buschur cat-back. Before i installed the dp, it sounded nice and deep. Now its a lil deeper and runs better but between 3k-4k rpm's It makes a horrible high pitched metal sounding flutter, almost like sticking a playing card in a high speed fan. What could it be?
Thanks,
Bryan Tracy

 

[Rick4g63]

Bryan,

- Safely Jack the car up where you can see the underside of the car clearly.
Have someone rev the car to that rpm (3k-4k) while you are under the car, look at the pipe and catalytic hangars and try to locate a flutter point.

- Is it a high flow or stock cat?

- Make sure the DP is secured properly at the O2 housing.


Good luck.

 

[95TSiNewbie]

I bought a long downpipe with a test pipe built in. Im going to re-torque the bolts again and see if that helps. Its weird that it only happens around 3.5k rpms.