I used an LS6 long block after I hydro-locked the original LS1 when my CAI took in water! With manifolds, the SLP Dual/Dual catback, 2.73's, 3000 stall, a lid and mail order tune the car went 12.55 @ 111.4 on Goodyear Eagle F1's! Overall I'm happy with the setup. My car is a daily driver, wet, dry, sleet or snow (over 200 miles a week) and there was absolutely no sacrifice in driveability. With a few more mods you've got the times in my sig. Of course, now I want more, but that's the name of the game right? Maybe some spray if I thougt the 10 bolt would hold up! Do some searching on here before you make your decision. I've found this site and the people who frequent it to be an invaluable resourse in deciding what to buy and what not to buy. Each time I've strayed from the recommendations I've gotten from this board I've been sorry. Take it for what it's worth and good luck with whatever you decide!