Well I dynoed my car last thursday and well the results were not good and have me confused as to what is the problem with my car. I have replaced the opti with a factory GM one and had the transmission rebuilt and puchased a PI 3200 converter. These were the only canges that I made. On a previous dyno the car dynoed 331rwhp and 407rwtq with a bad opti. Now with the new changes I have made it dynoed 305rwhp 363rwtq this was with additional tuning. Is there more to tuning than just geting your afr around 12.8 or so? Here are some of the things I have done to the car. XE 230/236 cam, TEA heads milled .30, Impala .28 thick head gasket. Comp Nonself aline roller rockers, MSD 6AL ign. These are things I have done to the engine. The car does however feel better than it did when I ran my best time. But the power on the dyno quits building at around 4300 rpms and the afr is around 12.6-13.0 though the rpm range

I have not a clue as to what the problem my be I am willing to pay someone to help me with this problem I think it may be the cam and or the tuning.
Any suggestions or questions?