I plan on purchasing an aftermarket y-pipe and was wondering if this would work with a greddy TT kit?

Thanks in advance

 

sure, the aftermarket y-pipes bolt up to the factory catalytic convers (or any hi-flow converter replacement)

We have a group buy just started on our new y-pipe, match that up with some resonated test pipes for some serious gains on the greddy setup.

 

Mine did, but had to have them install flex joints as I guess the down pipes/turbos were slightly different from headers, so if you buy one with flex joints you should be OK.