92 coupe exhaust system

right, i'm building up my newly bought polo [will stick up a build thread soon as this one's going to be a beast ] and i'm a bit unsure on what to do with the exhaust system.

i've purchaced and ashley 4 branch manifold as i've heard good reviews and i've been looking at jetex half systems too, but when it comes to the cat i'm a bit stuck.

do i go cat back and risk the chance of police doing me for emissons? (i already know the car looks bait and they're gunna pull me everyday, i might as well just write crack wagon on the rear window haha)

or do i splash out on a high flow cat? (been quoted a ridicilous price so i'd rather not do this one)

what other options are there, as i want to get as much power out of the little beast through the exhaust system as possible.

thanks,

tom.