I replaced my primaries with the high flow. Trust me, it is much deeper. My car sounded like "X" when it arrived at Fabspeed. When I picked it up with the high flow cats, X-Pipe and resonators, it was way deeper. Like "2X". Jeremy even revved it and pointed out just how much louder it was. The stock primary cats are a big restriction. Anything you remove from the stock setup will increase volume. Some things more than other things.
Originally Posted by powertrip
Crazy talk is thinking that your setup sounds the same as mine. I have no resonators and stock primary cats....signicantly deeper?? I think not
2009 Space Gray Carbon Leather E90 with DCT, Loaded except for that stupid cruise control and moonroof. Mods: AA pulley and air filter. Fabspeed 200 cell cats, Xpipe w/resonators and no secondary cats, Powerchip tune, Eisenmann Sport Mufflers, Xenon interior lights, Vorsteiner Rear Diffuser II, SWS8 subs, JL Audio XD400 bridged 2X200W