Airbox is the same. Motors are not hand picked. GM did switch to EPS Instead of hydraulic which frees up some parasitic loss. The NPP with valves open is also worth about 3. (Yes confirmed 3
). There may have also been some other changes but GM will not recertify an engine to achieve a higher SAE HP rating that is one its way out. The LS3 will most likely only be around through the next two model years of the Camaro and then I would guess you will see an LT1 (see Corvette Stingray) due to higher MPG available to help meet the CAFE standards
L99 automatic V8
LS3 Manual V8
Matt