check out the dynomax race muffler. we ran a 2 into 1 exhaust set up on my rig ,with a single bullet style. it has a really good sound for a inexpensive muffler.
true in stock form, if you start buying after market parts for a late model motor , it is cheaper to build old school. ive personaly never been able to run a stock motor ,i like a little more spank in my crank. stock parts tend not to live above 7000 rpm.