Many OEMs and even race engine builders will REDUCE bore size for the gains in cylinder strength/sealing. What you give up in displacement and valve shrouding can be made back with the ability to run higher boost with a more rigid cylinder and better head gasket seal.If we were to get a 4.8, I would have to think it would need to be twin turbo. GM is supposed to have a new 6.2L DOHC that is going in the Vette, and likely the Camaro. It's rumored that Dodge will offer the non race tune Demon engine to their lineup. Who knows if the latter will wind up in a lighter vehicle. I just don't think a S/C 4.8 will be able to hang with the competition mod for mod.
The difference in 4.8/5.2 is negligible if the 4.8 can run 10 more PSI.
-J