All the new straight thru design mufflers are ...surprise just like a glass pack and the new "glass packs"have no glass in them just like the exspensive flow thru mufflers and almost exactly like a straight pipe,How can you get less flow with a 2 1/2 inch hole thru the center
It does not get any cheaper or better flowing than straight pipe with no restrctions,if looking for power and no restriction,cherry bombs,anything else is just looking for a certain sound and thats ok too ,but to some go is better than show or sound in this case.
I have one on my truck with a hot 305 ,rams horns into a single with no pipe currently after the bomb.It sounds ok,but I am sure there is no impedance to flow at all from it.
http://www.youtube.com/watch?v=ld4vfbizOBI