As of right now I have true dual 40 series flowmaster delta flow with a magnaflow x-pipe. They come straight out the back with two big 4inx22in crome tips.

Would I get any reduced back-pressure by getting rid of everything from the mufflers back and getting turndowns?

 

yes, i did that on my truck with a single 3" and i noticed a difference, if you dont want noise though i wouldnt reccomend it because you will definately get some more noise

 

I would say no. With those 4"x22" tips how much could you possibly lose? It will definitely be louder though.

 

you have to take into consideration the extra 5' of pipe between the muffler and that 4" tailpipe. there is a lot less restriction with no pipe than 5' or pipe