Assuming it's a stock car, but with appropriate chassis and wheel/tire upgrades to handle the extra power, I would think you will need at least 850hp to get you mid 9s. Late 90's I ran mid 10s in a stock steel body and full interior 68 charger. Had a Indy headed 451 that made about 730hp. No cage, 8 3/4 w 4.30 spool, 5200 converter, 8" steel wheels w ET streets.