[Diesel Nut]

Stainless will cost a bit more. Aluminized is cheaper. Aluminized is easier to weld on if you ever need to.

I got a 4in MBRP stainless turbo back with free tip for $520.00 delivered

Thats about right for the turbo back kit #6004409

Material has no effect on sound. Personally, I think the Dmax soinds killer striaghtpiped.