Without the nitrous try uping the a/f. Stock a/f at wot is usually about 13:1, and then about 12.5:1 up top at wot. Each setups different but i'd try anywhere from 12.8-14:1. Get on a dyno try some different a/f between there. On the nitrous dont try anything higher than 12.5:1. That 11.8:1 would be a good starting point.