I bought Howards cam LS3 specific roller rockers for my 2013 Cam. SS. They were advertized as direct fit with no need for any changes includeing Valve covers. Totally untrue 10 of 16 hit covers and one had to be machined to fit into head casting on its backside. Got a store credit at Summit where I got them. Currently useing factory rockers while awaitig Harland-Sharp rollers. At least they tell you upfront you will need taller covers or a spacer of some sort. Scorpian makes the same claims as Howards, and I understand they have the same clearance issue's. Car revs as high with factory rockers but doesn't seem to rev as fast. Friction I guess or maybe a little difference in lift. Hope this is helpful for someone. I've got a lot of waisted time and money in the Howards Rockers. They work but you got to get different covers. period.