The first thing I would suggest would be the BMR anti-wheelhop kit, as well as the GM Racing "Locking rings" (just delryn bushings)
That will cure the wheelhop, which should be priority #1
After that... the best bang for the buck modifications are as follows, IMHO..
Heads/Cam - You can gain up to 50hp at the wheels with a good heads/cam combination, and it should make more power throughout the entire band, price should be around $2k for a decent set.
Magnacharger - for about $6k you get an extra 140rwhp -- its a bit pricey, but probably the most power you can get easily.