tonight i was taking off my gruebee skyhawk 5 g head and replacing it with a angle fire head which looked like it had a bigger combustion chamber to me bigger = less compression but we will see. But anyway i took or the the head and there it was looking at me dead in the eye the elusive steel lined cylinder i saw it with my own eyes no more wondering people if you don't believe me remove the 4 bolts and look for yourself it IS there!!!! they didn't lie to us other people that know for a certain that they don't have one no you don't because they do and the change in type of metal is very noticeable