Try finding a custom exhaust builder in your local area. They will discuss what you want to achieve - make it sound as you want it to and be able to advise on the size of bore etc.
I just got my new Stainless Steel Cat Back system made and fitted for £240 locally. Sounds really nice without being too overt loud / boy racer and the guy who made it has introduced me to another recommended company nearby who do remaps for rally cars and track cars.
I fitted a Ramair cone filter this evening too. Altogether pretty chuffed - nice deep exhaust note - not uncomfortable in the car and it feels quicker already - although that may just be throttle response as opposed to actually increasing any HP. Could be in my head but I had a blast on a hilly country road close to home. Can't wait to get it re mapped!
That actually sounds like a brilliant idea. There's a place quite close to me. I need to get under the car first to see if it's worth fitting the new exhaust cause when I floor it I can smell burning or exhaust fumes.. Obv not good so need to find out ASAP before I put cash into her
A vote here for Powerflow (burbles nicely, not too loud). Quality of sound depends on fitter but mine was great and did it to my exact spec (St Albans). Def worth spending a night or two on you tube to answer this question though!