Looking for some one who has installed these. I have placed an order for the headers with Tbyrnemotorsports but unsure which primary size to get. My truck is a '02 Chevy 2500 HD, is 1 3/4" or 2" diameter primary tubes better? Any one know? I also intend to use the factory y-pipe and cats, then to a FLO-PRO muffler.
(I also ordered the Volant Air intake, velocity stack, Magnacore wires and Westers computer tune, I will let you know the results. Doing my part to help the economy!)
Thanks,
Steve

 

That 8.1 has 496 cubes to it, I would go with the 2" primaries for sure. Its a bored or stroked 454, cant remember which.

Check out these mufflers for your HD. http://www.flopro.com/FP2500oval.htm

peace
Hog