I have a 2007 Pontiac Grand Prix GXP. I want to upgrade to LS7 lifters. Will I lose my AFM if I do this? Will I need to buy extra stuff to make the lifters work? If so what would I need?

I'm pretty sure if the lifters are changes then DOD is lost. Then i think you have to change the valley tray too. Are you talking new valve springs or lifters? Lifters wont give any performance benefit, unless your swapping in a new cam and you need different lifters.

what do new valve springs do?

the ones in our cars are a bit weak, stronger springs would allow you to spin the engine at a higher RPM without valve float. Most guys use LS6 springs as a replacement. Why do you want to upgrade the lifters?

I am getting the cartuning intercooled turbo. I am getting the turbonetics T-72 turbo as an upgrade. Kevin Margitta said that i would need new valve springs.

Well well, then yes you will need upgraded springs. Any upgrades to the trans yet? If not I would put some in your plans, but i'm guessing Kevin went over that stuff. When are you planning the install?

i am getting his built tras. 3" downpipe upgrade, and am going to have him instsall the who thing plus a custom tune just for my car.

Very cool, it'll be a hell of a ride man!! Something like this should work for you http://www.jegs.com/i/Comp+Cams/249/26918-16/10002/-1
Can I ask what the total will be??

10.5K for the whole kit, upgrades, install and tune.

Not bad considering all that will be done. Keep us posted on how everything goes.

actually it will be 11.15K