Fair enough. I never tell anyone not to use them, if they want. I guess I'm just not into making noise. I like a mufflered sound better than open, I have raced for a lot of years with mufflers on, always.
As for free flowing. EM , the same people who choked a 700 hp motor to make the cutouts look good, tested four mufflers on a 1000+hp motor, and MADE horsepower with one of them, and the WORST one only cost 15hp.
Yeah, i never got the full open headers thing, i like to hear my motor and if any problems are starting.. I watched a buddy run 9's in a C5 with full stock exhaust.. didn't seem to need a lot of noise to do it :)