I'm looking for a quiet preformance muffler, I've been told that Borla XL's are a quiet high flow muffler and a good choice for a 450 hp big block street car. Anyone tried these mufflers? Dave

dsr, Borla makes the best muffler on the market, bar none.

Dynomax Ultraflo....unless that is, you're looking at them becuase they are stainless.

Borla does not come close to the best muffle when it comes to there 3" xl’s. I cannot speak for there other xl, sizes but there 3" cork up to 2.5" on the inside (something you want to look for). Kinda defeats the purpose of having a 3" exhaust. When I called Borla regarding CFM rating, I was told that they cannot disclose that information for that muffler graemlins/clonk.gif (I do not know why they would hold that back unless they really suck). I decided to go with Magnaflows, which are basically the same as Ultraflows, true straight through design, offered in a polished stainless case, and a published CFM rating.

I seen a list of about 10 2 1/2" street mufflers, Borla XL was at the top for quiet operation and second from the top in the flow department, I think it was 373 cfm flow for the XL muffler. I can't seem to find the list now. Thanks for your replies. Dave

i posted a whole bunch of muffler test info a while back. i think that's probably what you're talking about. perhaps someone should set it up as a reference thread, seeing as these topics come up fairly regularly... muffler comparison thread (http://www.chevelles.com/cgi-bin/forum/ultimatebb.cgi?ubb=get_topic;f=4;t=018760)

I run 20" case 3" dynomax hemi super turbos which made the same exact hp as tiny spin techs on the dyno, and with an x pipe, people tell me they can barely hear the car.

mattt