What gives the JH 8.5:1 and the DX/KT 10:1 compression? (2.0 Q inside)

Is it all in the pistons?
ETKA list's the JH and DX head under the same number but the camshafts are under different codes (JH and EX is 049 109 101 J, DX and KT is ether 049 109 101 N or 026 109 101 G). Does that mean that the KT has a "G grind" or "N grind" cam?

The pistons are DX/KT/EX "026 107 065 R" and the JH's are "026 107 065 Q"

I'm asking this becouse I'm going the 2.0 audi block root (not 3a but AAD. Suposedly the same basic block) and need to pick which head is going onto the block (I have both at home).

P.S. Nice forum you have here

 

I don't really know, so here's a reply to bump it back to the top.

I'd suspect one has a bigger dish in the pistons than the other.

 

From what I was told elsvare the compression is changed by the pistons. Still don't know the diference in camshafts.

 

same rods and crank, piston crown is different.

 

The pistons that have a 20cc dish will result in a 8.5:1 compression ratio. The GTI engine have only a 10cc dish. This applies only to the 1.8 L 8valver