biggles010

Got a new cat back by pro tuning(complete ****, said bolt on but wasn't) it sounds great in neutral, i can rev it up to limit with no rattle. But as soon as i put it in drive i get a rattle when it goes over 2k rpm.
I have no idea why and this is crazy annoying. Please help with any suggestions. Currently not running a cat(it is legal in my area).

Sharkzilla

Jack up the car, get under it, gently shake the exhaust around by hand, listen for metal hitting metal.
That's what I'd do, anyways.

easis300

Most likely your piping is hitting the lower control arm on passenger side. There is very little clearance for exhausts on our cars!

timmicles

Agreed for lack of clearance. One thing for me though, I've had rattling and fixed it with new exhaust mounts.