need cat-back advice

I need some cat-back advice. I have a borla side exhaust system on my '96 cobra(@ 32k miles) and the mufflers blew out. I'm debating on whether to change the whole cat-back to a rear exit system or to swap out the mufflers only(rest of it looks okay). I will probably add a blower in the next year or two. Thinking of a magnaflo system because a) stainless (i live in maine) b)affordable ($400-450) and c) bolts right in (I never welded a thing in my life). Doesn't side exhaust cost HP (especially if I add a blower into the equation)? Also might be interested in a complete exhaust system do-over (i.e. long tubes, short h-pipe w/cats, cat-back) if I can find one in stainless and i can afford it. Will magnaflo system work if I change headers and h-pipe later?