Does the 2.5L use a different exhaust?
 

Wondered if a Prodrive backbox from a newage WRX would fit an '06 STI, or have they changed the exhaust set up for the 2.5L?

Exhaust size the same so the back box will fit,all they have modded is the flange between down pipe and second cat they have put it further forward.No reason just to awkward ;-)

Ian