I have a 94 WRX with an HKS superdrager exhaust,just wanted to ask if i was to change the center box for a straight through pipe,will it make it louder and how much louder? will it increase bhp and how much if so?.i will prob go to RCM because there the closest to me.
Any help would be great.cheers

 

The removal of the centre pipe for a decat pipe on mine has made the flat four rumble a bit louder (not much) and it does feel a bit faster (unproven).

But I would say get one