Saltman

iTrader: (3)

Been searching and doing research but haven't found an answer to my question yet.
I currently have a topspeed y back exhaust and about to install berk resonated test pipes. I also have z1 CAI and plan to get a ported plenum before tune. I'm looking for gains but my question is should I leave the stock y pipe, or buy a y pipe or make my own dual exhaust with x pipe to a modified topspeed exhaust?
I'm looking for minimal to no rasp. I know that a 2.5 to 3in y pipe causes rasp so I'd be looking at the motordyne if I decide that route. Is it even worth the hassle to change out the stock pipe with these mods?

slartibartfast

iTrader: (7)

From my somewhat limited reading, the pipe isn't the cause of rasp, it's the removal of resonators. Typical aftermarket pipe size for the G37 is 55 mm (2.25"). 3" makes sense if you're boosting.

Saltman

iTrader: (3)

Let me be a little clearer... I've read that the Megan y-pipe or something similar with 2.5 in inlets to 3 in outlets mated to the topspeed exhaust which is 60mm or roughly 2.25in - that's what causes rasp. Better to have a 2.5 outlet y-pipe. Hence why I'm considering custom x or staying stock. Topspeed already has resonators on it.