I'm thinking about canning the idea (cat back system) and just upgrading the cat to a high flow and maintaining the stock exhaust. As far as power goes, I'm really only looking for 280-300rwkw long term. Looking at other threads it seems that the standard exhaust is capable. Obviously I need other components such as injectors, air intake, intercooler piping, and a tune. Saying all of that, I will probably wait until I'm out of warranty and can afford to do it all at once. For anyone who has upgraded the cat to a high flow 100 cell and kept the rest of the exhaust stock, is the exhaust note noticably deeper/throatier than when it's stock?