My first weld ins were Dynomax Bullets...the sound was very nice and deep below 3000rpms and it just screamed at WOT. These mufflers were cheap as crap and of great quality (34 bucks a piece)
Then changed to Spintech ProStreets and almost kissed my muffler shop owner when he started it up...everything I loved about the Bullets and then more...loud, hollow and lopey at idle, bubbly at 2000 to 3000rpms and then "watch the f**ck out for cops" at WOT, heck probably just one decibel quieter than SLP when you get on it hard. These mufflers not only flow just like the straight thrus, they sound sorta chambered, best of both worlds.