straight pipes and inserts

If your going to go with straights, go 8" with the baffles in them already. 6" are old school. Make sure when you order them that you tell them you want baffles in them.

 

7" go good on a aero cab. But the inserts you talk about only go in 7's and 8's if im not mistaken, I could be wrong.

 

dynaflex makes a 6" center spool called a "Quiet pipe" should do the trick... your local chrome shop should be able to hook you up

 

I just put inserts in my 5" straights. They make them for every size. Did not quiet the truck down much but took some of the bite out of the sound. Performance is the same and I couldn't tell you on the milage. They really do not restrict the air flow at all.

 

7 inch quiet inserts are 5 inch straight through
6 inch quiet inserts are 4 inch straight through

I like my 7 inch pipes with the quite inserts, you can still talk to your passenger with out shouting.
but put her on a hill you still here her talk.

The jakes are alittle on the noisy side