I have now got myself a few Holden 6's while in the process of getting my HX on the road it came with a barely running 5,000km old HX 202 (80thou over) with Low comp head and I have put a Blue 3.3 in it that has a H cast into the head. I assumed that all Blue 3.3's were low comp. Anyway I bought a Blue 2.8 and was going to use the High comp head on my HX 202. My question is if my Blue 3.3 head has a H cast into it, is this infact a 2.8 head already? if so I bought the Blue 2.8 for no reason as i already had a small chamber head.