Well as one that follows it closely I can give my opinion...First of all, Callaway gets ZERO support from the factory. Callaway buys the Z06's complete and strips them. Second, I basically think that Chevy wants control of a great deal and this does not fit Callaway racing. There was some cooperation with the C4 LM, but I think very little. Funny part is they are damn good without them.....As far as ALMS, I would guess that the reason is simple. Callaway Racing is in Germany and the FIA is in Europe. THere is no real Callaway racing structure in the US. Ernst is really the man behind all of the racing and he is there. Likewise, the racing in the FIA is most likely more cost effective in that it is based on customer teams. While ALMS is layered, the lesser tiers are kinda unknown and in Europe GT racing is like NASCAR....even the lesser levels. Therefore makes sense to me.