Do most aftermarket y-pipes match up with the stock exhaust? Also, should I spend the money on a y-pipe or are there better "bang for your buck" mods I should get first. I'm planning on aftermarket hfc/y-pipe with stock exhaust.

All I have is high flow cats so far

 

More info is needed what y pipes are you looking at year of ur car

 

buy my aam 3 inch y

 

Look for a nismo ypipe. Or if youre rich get a motordyne xyz pipe