I think i have decided to go with the Flowmaster 40 series w/0 delta flow on my 98 GMC 5.7L ext cab truck, but will i get more sound by using dual mufflers or should i just use the dual outlet muffler?
I think the sinlge will give you better resgination sound due to increased back pressure.I have that same system w/ a single muffler & it is not real loud in the truck but definitly sounds crisp when you hammer it.
If you go duals i would definetly go w/ headers and a split pipe. I have true duals w/ flowmaster 40's on my Blazer now and it sounds ok, just not as nice as a some other trucks around(my fav sound... dual cats w/ no muffs). It may change if you are still using a cat though which I'm not. A single w/ dual outs sound really nice and will be better then a stock exhaust, but it lacks the flow higher in the rpm range.