Originally Posted by PatrickfromMD
I have read much of the same for the L99 motor (I have one on order).
In addition to not needing as high an RPM due to less cam, I read that the AFM does impose some restrictions to the valve train at higher RPMs.
This should not be an issue if you keep the motor stock. If you are looking at adding traditional performance mods, then this RPM limit needs to be taken into consideration.
Iím keeping my ears open for ways to beef up the valvetrain to handle more, but have yet to see any useful information short of removing the AFM
Also, the L99 may have the same heads found on the L76, since that too has AFM. Although the castings are the same as the L92 heads, to save costs the L76 (and possibly the L99) has heavier solid valves vs. the lighter sodium filled L92/LS3 valves.