I was in the process of installing my new true duel exhaust, when I realized the rear mufflers were going to have to be welded. I basically wrapped everything up, and drove the car home open X-pipe. The exhaust basically dumps out the X portion. It is not too terribly loud, and I barely noticed any loss of torque at cruising speeds. The car feels like a beast midrange and top-end, my question is did I actually lose power, or is it the placebo effect? I know no back pressure can kill torque, but would power actually increase?

 

If you have good straight through mufflers, you have no backpressure in a dual system anyway from the xpipe back...so it would probably be the same as if you had mufflers on there. You are most likely feeling the effects of adding the duals, which will increase your midrange tq.

 

Ahh. That makes sense. So basically all the mufflers would do is quieten the car down a little correct?

 

Yes correct. Adding mufflers on that system would muffle the decible level moreso than not having mufflers on there, but wouldn't do anything to change the backpressure that you describe.

 

So basically, I may lose a little low end, but make up for it top-end?

 

Actually, I don't believe our engines loose any bottom end having a free-flowing exhuast. It used to be that you had to have backpressure of some kind, to have good tq down, but maybe someone else can colloborate, I don't believe that to be true with the ls1, when talking about tq, at least in this situation (header primary size is different).

Basically a good set of true duals is as free flowing as straight pipes, that's why when running duals you don't need a cutout because of how free flowing it really is. Having an xpipe there just adds more tq than is already there, so it actually flows better than straight pipes, kind of like how shorties are out-flowed by LTs, even though both have primaries and a collector...