Welcome, looks a good project mate, keep up the good work, I'm on a standardise project at the moment with my MK4, mine was proper chavved when I bought, it, now it's starting to look normal again lol..
As for the exhaust, for £500, Top Gear in Bridport can do a full custom....(CAT, Middle and Back boxes) stainless steel for that money, so shop about, you can pretty much tell them how loud or quiet you want it, S/S is defo the way to go..have fun
Warren