The Y-pipe doesn't nor shouldn't have mufflers. Perhaps a resonator where the converter went; however even that I would recommend further downstream...
SHOShop mandrel Y-pipe is $150
So less than that for a crushbent
What people should do is get together and contact MSDSInc about a possible one time batch of their Y-pipes.
Probably unlikely, but I think the turn out would be greater than expected considering all the SCCA folks could use it since it doesn't touch the stock cat and the other folks could make whatever pipe/cat/etc mix after it they pleased.
