i have an 87 iroc 5.7L, and was wandering why my exhaust shakes when i am in park or just barely moving. i was aslo wandering if when i put new headers on my car if i should run 3 in. exhaust pipe or not. my car is factory now other than a computer chip and the headers.

 

It's normal for the exhaust to move around a little, but it should not be shaking violently around or anything like that.

3" pipe is definitely recommended.

- Justin