If you want to go catted I would suggest getting a pipe with the cat as far away from the turbo so it gives the air flow to balance out and flow through the cat easier. If you want to go catless, then invidia is a great brand. I picked up a barely used Harman Motive Catted that is Grimmspeed heat coated for only $400. Catted costs more, but gives you piece of mind that you still have a cat. Catless is cheaper, but I don't see it affecting power gains until you are a high hp car.