A few downpipe and exhaust questions

[Totaleclipse04]

1) A friend of mine ran a stock turbo in his 95 gst he then put a full 3inch turbo back exhaust, would this burn up his turbo by allowing it to free spool?
2) I have a 97 eclipse GST running stock turbo intake filter with adapter and a custom cat-back exhaust. I want to run stock turbo for now but convert to a T3/T4 which will let it breath better and allow the car to run perfect a 2.5 inch or 3 inch turbo back system?
3) In my state that my car is registered in there are no smog regulations so that being said i could run a test pipe if I choose to. Which would give me better performance a test pipe, a highflow cat, or one of those things that eliminates the car by bolting a pipe in the cats place?

I would really appreciate not getting flammed and all that i didnt have the proper time to research my questions I'm on break and was thinking about this while working. I really appreciate any help i can get from you guy's Thanks.

 

[DSMcamaro]

1) no
2) either system will work, most people would probably say to go 3in.
3) A test pipe IS one of those things that you bolt in place of your CAT. Go with no cat if possible.