I realize that 3/10 is alot to gain by just changing heads, and i am doing a few other things......but i think my old heads r the bottle neck and the new ones will make a diffrence.......i would have went to the afr 227 if i had more cubic inchs.........want i want to do with this car is to run around 10 seconds flat...........it is funny how it works in my class at the track most people r in the 10's but very few r close to the nines........so i guess if i was around 10 flat i would be one of the faster cars.....hey we r men it is all about having fun but still going faster...............i was just thinking about the 3/10 tenth gain again...........u know i have changed spark plugs and gained a 1/10 and have changed jets and gained a 1/10 and a few other things..........i am hoping that i gain at least 3/10 i am planiing on doing a few other changes.....going to try a few diffrent carb spacers.........ladder bar postion............carb is getting done at a wet flow bench right now.ceramic coating the headers..............thanks for the input