Have a word with Charlie at http://www.pro-speedexhausts.com
before you make your decision on which system to go with.
I was looking for a S/S system for my V8. The collective experience by several members on this forum was that nothing off the shelf was available without major work at home to make it fit.
On the advice of a happy customer / forum member, I spoke to Charlie after ringing around the usual and not so usual stockists. Pro-speed manufacture the exhaust on the car. He listened to what I wanted from it, then quoted a price which undercut the the cheapest standard off the peg system by 35% and the most expensive by 150%. He made me a single pipe V8 system, tucked up to clear the nasty speed humps I have to straddle in my neighbourhood, with a single resonator box and back box. I wanted a mellow V8 burble at idle, a rorty noise under acceleration and a relatively quietish car at cruising speeds and he nailed it.
The considerations for me were; Pro-speed exhausts are in Cardiff and the car has to be driven there. I saved a considerable amount of money, for a system made to my requirements, that has a lifetime guarantee whilst the car is mine. I didn't have to make it fit as Charlie made it on the car, while I waited, and did all that for a lot less than an ill fitting system that I'd have to fit myself. It worked for me several years ago and the system still looks as good as new.
I appreciate the relative saving for a 4 pot could be less than an 8 pot, but have a word with pro-speed to see if they can help.