Please search. This is brought up constantly. There is even a sticky at the top of the engine forum section that talks about swaps. After you have exhausted all your research options THEN come ask.
i wouldnt bother upgrading the y7 unless you want to put a y8 or z6 head on and intake manifold, should gain about 20hp just from that. if you have money go turbo
Boost it.. if you cant afford it.. do a mini-me swap on it.. you can do that for about $150-$300.. and if you really wanted a better deal.. get the y8 head.. send it to a machine shop and have the head worked before you put it on.. best bang for your buck IMO