Got the one chambers on and.....

I am not sure that 0 backpressure is good for your valves..with those warlocks...can anyone confirm?

I think you're right but i'm not 100%. I do know that when i switched from actual mufflers to those straight-through bullets, i not only lost low-end grunt but my car now gets about 20 miles less distance per tank of gas and feels like its working harder all over the powerband. As for the noise, I don't think you're gonna get that flowmaster note much louder unless you put in a more aggressive cam....some1 correct me if im wrong on this lol.
 
UPDATE:
Well the one chambers are starting to sound pretty good to me now. They are a little high pitched at higher rpms but down low it does kinda sound like a 40 series but louder. So all in all I think that they are a great sounding muffler and if your looking for the 40 series sound but a little louder these will be as close as you are going to get.