Originally Posted by audiohigh
I've got Eisenmann. Looks good and sounds great. Got one of the cheap-o eBay diffusers though. 3d Design has a great one but it's really simple and is off the charts expensive.
Here's a thread where I posted the end result.
A little note though. No matter which quad you go with it's mostly going to vent through the drivers side unless you go all custom and have it balanced better.
How much you paid for your quad exhaust?