Yeah those cats r restrictive as hell. I would have gone off road with mine but I needed cats to pass inspection. Lol those SLP high flow are basically hollow any way. Sounds good though. You need to wash that mach lol
2004 DSG Mach 1: K&N FIPK, X-Pipe with SLP High-Flow cats, Flowmaster Super 40s, MM C/C plates, 4.10 gears (auto), PHP Intake spacer, Steeda Tune
Last edited by Bluestreak69; 02-05-2018 at 12:40 AM.