You do realize the factory system has the y-pipe after the cats, right? The banks don't collect into one until just after the driver's side post- cat and after the crossover pipe that comes across just after the passenger side post-cat.
I didnt realize that the Y-pipe on the X is after the Cat. Most Y-pipes I've seen or worked on were in front of the cat, right after the exhaust manifolds. Thanx for the correction Brent.
Do we even need a Y-pipe or can we change it to dual exhaust?
Any benefit to going with a single cat instead of the two or four? Will this screw up the ECM and trigger the SES light?
Just throwing out ideas..