Exhaust size?

2 1/4 that's for slant six and 318 cars.:toothy10::toothy10:you've spent the money on good quality headers now don't get cheap on the rest of the exhaust..trust me your 340 will appreciated the extra breathing room,i run tti's with 3"aluminized pipe to the mufflers 3" in 3" out,with 2 1/2" tailpipes,factory stainless tips.. sounds and looks great...yes it can be pricey but when done properly its worth every penny spent..oh for your car i think 2 1/2 all the way would do the trick..