LSx Valiant Build. Take a look inside...

I guess it all depends on your end power goal-constricting to a 1 5/8 will restrict some. Are you sure you can't reroute them up and over then back down kinda like A body headers normally would go? I know what you're saying about the exhaust pattern being different, but I guess I'd have to see it to wrap my head around it...gotta have a good visual.