So I brought my car to the track for the first time yesterday, first run ran a 15.0 with a shitty 2.4 60 foot, second run tranny grinded into 2nd and wouldnt even go into gear.

Tranny grinds when under heavy acceleration and usually in vtec. But under normal driving its fine. Should I rebuild or replace? I tried GM synchromesh, but it doesnt seem to help.

 

your syncro is shot.. common on cars that have been abused at some point (I'm guilty of doing that as well). If you take the tranny out yourself, a rebuild won't be to much.. If not, look at around 1000$ to replace..