The rule of thumb with our cars exhaust is H Pipe for Chamber, X for a through muffler like SLP, Borla, Magnaflow. If i were you i would go with Pypes high flow cats (i feel like im a promoter for them but they sound sick) with an X, the Cats will keep the rasp down and make the exhaust slightly deeper, and the X will give you the best results with the SLP's