From someone that I would consider reasonably informed. HSV will release a 400kw low boost "R" with the heavy duty diff soon. Evidently are now taking orders so check with your local Holden Dealer as emails have gone out to dealers.
Seems to make some sense if the Redline is getting the L99/LS3 so HSV need to fill the gap between the Clubsport and the GTS.
Cheers, Matthew