I just had my side pipes put on my 01 sport 4.6. Got a 40 series flowmaster and it sounds great. i was wondering if anybody has run no muffler and if it sounds good or not. i was also wondering if removing the downstream cats would help with power/sound and not affect the engines reliability and condition. help would be greatly appreciated.

 

There are plenty of guys on this site that opt to run w/o a muffler. Not sure why. No back pressure=No bottom end (normally). Too noisy for me personally. If you have O2 sensors after the cats, removing the cats will most likely throw a code and give you a "Check Engine" light. Removing anything that drastically lowers backpressure could possibly do damage (valve problems) over time. The benefit of removing cats can only be seen in most cases on a dyno sheet. Blown/turbo motors can obviously benefit at WOT, but a naturally aspirated street driven motor relies on a certain amount of backpressure for part throttle/cruise operation.

SL

 

Ditch the stockers, but replace them with Magnaflow cats. Well worth the $80 or so a piece, and you're replacing 4 cats with 2 and getting the same emissions control.

-Flea