Was in doubt between Super 44 or Delta Flow 40. Didn't want excessive hum. This muffler is very good, I just replaced the rear mufflers, otherwise the exhaust is stock. There is a hum while driving, but nothing annoying. And the sound outside is very deep and good up to about 4000 rpm. After that I find the noise quiet (may need a bigger motor for full noise in WOT) but the overhaul is fine with me and I don't regret getting it