Im scratching my head here..... Why the hell would you want to put a Navi 5.4 in an already supercharged 03 cobra? That would be a substantial loss in power, stock vs. stock, and a tremendious loss in potential power. Maybe I've been missing something....
custom dude. there is a thread by BOSS330 in the corral. get a hold of him, he can steer you. they need the car to make them. you can probably mod some GOOD shorties to fit. 1 3/4". you can still exceed 450 rwhp with them.