Exhaust??

Ya it can get pretty expensive but I rather save up and buy the good stuff now and do it right the first time, vs. wasting my money later. I will raise the boost after I get an intercooler and probably other things. Probably up to 8-9 psi...Do you guys think I need to upgrade my internals? If I got a 3" all the way back now with out the turbo installed will it do any harm? Say I do go with a custom pipe what muffler should I go with? And should i just a high flow cat or just a flange that will accecpt a 3' pipe? All these questions.........and in need for answers (I need some help) Thanks alot