So much choice to choose from depending on your budget and whether you want a part system, full system or just a back box.
As example;
Low end ~ Cobra, Japspeed, DC etc
Mid range ~ Invidia, Magnaflow etc
High End ~ Blitz, Greddy etc
Dogs danglies ~ Motordyne, Ark, Borla etc
Although tbh some of those makers do make exhausts in various guises that will meet different budgets.
Have a look at the Professional Traders sub section for some of the traders that can help you part from your money.