hey guys
my exhaust consists of R34 GTR dump pipes(60mm outlets) going into 2x60mm to 76mm merge front pipes, into 76mm decat, then 70mm to 80mm "hks legal" cat back.
all this time i though my cat back was going from 76mm after the cat then opening to 80mm but i had it off the other day to fix a leak and measured inside the flange and found it to be 70mm inside diameter !
would this step down in exhaust flow cause a noticible restriction? also its a very quiet cat back, got afew little bends after the cat going into the center resonator(straight through type) then afew more little bends (with a nice almost golf ball dent in it too lol), then a big S looking bend near the fuel tank before exiting out the rear muffler.
im organising a final tune in the coming month or so, is it worth me ditching this and getting a nice 80-90mm stainless zorst? (kakimoto regu 06&r mmmmmmm )