Keep the 4 stock converters, take the old Y out, and replace with new Magnaflow Y pipe, then go back to a Extreme 1 chamber IMCO SI DO 2.5 to 2 2.25's run out behind the back tires at a 45 degree angle. What do you guys think? Any comments, opinions??

Darren

 

If you are replacing the factory Y-pipe, go with the double 2 1/2" to a 3" outlet. This doesn't hurt a thing especially going into a single muffler with dual outlets. I skipped the Y-pipe replacement, just took out the old one and went with dual pipes into a dual inlet muffler.

 

SI Dual out slow down exhaust velocity and as a few people have said will harm your performance.if u want more performance go with a 3" from Y back or true dual with an X or H pipe 2.25" pipe for the 4.6 and 2.5" for the 5.4" is optimal for exhaust flow velocity