so whats the CC and chamber difference between a Pro XS and a early Pre 2000 optimax head, both seem to share the same (visually anyway) pocket and chamber layout.. i know the XS uses domed round pocket pistons. vs flatter oval and early opti flat tops, just trying to get the most bang for buck.. was there any difference between the 843020-21 C2 on a 250XS vs the current 08 revision??? im doing a small upgrade to my opti and need cylinderhead opinions..


i am looking at 3 sets... 1 set is a 2004 250XS set thats been painted black.. 843020/21C2

a set made from 2 motors but both are 07-09 225 PROXS but are the A06 revision of the C2 head PN
or a 99 set that appears to share the same chamber layout as the 842020/21 heads

obviously ill be programming the ECM because i took off the big round chamber heads that im really not impressed with..

have the set of round pocket domed pistons to match in hand