lemme know if you do find out they can hold more.. i know the new ZO6 springs hold like .600 lift? Dont quote me though...

metal, keep in mind you may need a stall with those 216+ cams. If you get her in and bottom end suks, dont be upset at first. Then again, it might go in and bottom end might be better than ever. Every truck seems to be different. I just know kine lost bottom end below 2600 rpms.. light throttle requires more effort to get the truck moving at hills. But get above 3k and MUAHAHHAAHHHAHAAH