I was looking to have my wrx taking to a shop to have stage 2 and tune done. They gave me quotes for what they use the most on subarus. What is the difference if any between turboxs and invidia exhaust wise? And is it better to have catted down pipe or non catted? Now with intake which is better aem or cobb? I've seen all these names and prices every where but I don't know what to choose.