Originally Posted by hngonzalez

You will never match the rumble of a boxer engine with any other engine. That sound is intrinsic to a flat-4 or 6 type motor with unequal length headers to get the exhaust pulses to sound that way.

As for exhausts, anything over stock will produce a deeper growl than stock. Berk, Stillen, Invidia, and Fast Intentions (might be a little more?) are probably in your price range, as well as ARK... but thats a gamble.