It would be cost effective for you to go with a s/c.. The turbos for this car can get really tricky to keep up and require a lot of tuning.. must harder to install basically.
If you go with the s/c I wouldn't recommend going with n20. Maybe a 50shot but anymore you'll have to set your timing back a few degrees.
Get you a nice exhaust system, headers, maybe stage 1 cams (vt makes some nice ones) and you could see 11's with some DRs. in the 1/4
(thats with the s/c..)
also i'd recommend a lobe seperation of about 113-115 with new cams. else you could end up blowing some of your boost through your exhaust!
keep away from the nitrous with the stock bottom end!! Spells detonation all over it!