How similar are the L99 and LS3
 

I know L99 is AFM and LS3 is not. but im more asking in terms of aftermarket. will headers or intake be able to fit for both. my main concern is that if theyre not then that will bring price for aftermarket parts up due to economies of scale

I've assumed from all the rumars that they are indentical in respect to aftermarket performace parts, but maybe not...something is taking away HP from the L99. I'd like to know the exact differences too.

AFM and a different cam are all that I know of.

it could be different valves, just like in the L76. If the L99 does have the solid valve's, that could spell trouble when attempting to change cams. The regular LS3 has hollow stem valves but we've seen with the L76, which the LS3 actually borrowed from the L76, that GM cut corners and went solid on the valves since the if too had AFM and only revved to 6000. All that weight in the valvetrain may cause valve float with a bigger cam.