http://cgi.ebay.com/ebaymotors/ws/eBayISAPI.dll?ViewItem&item=1828390716 THIS IS A VERY POWERFUL MUFFLER - LOTS OF HORSEPOWER WILL BE GENERATED CARS LOOKING AT THAT WILL HAVE ENVY WITH THEIR CHEAP MUFFLERS!!
Well the muffler is one of the limiting factors in the Exhaust and teh Exhaust is a VERY big part of a HO motor
not exactly true. If you're using a decent sized 2.5" exhaust and you put on full 3" exaust and removed the cat, it's not a giant gain.
Exhaust tuning IS an important factor in performance. A naturally aspirated engine will not, however, have big gains from just a muffler. First, a header system must be utilised to "pull" exhaust away from the engine. at that point a free flowing muffler will help some, not that much though. Only turbo cars will see significant gains from just a muffler. A free flowing muffler reduces backpressure and enables the turbo to spool up faster.