AAZ headgasket!
the only problem is that the 1.9 hg thickness is a little different than a 1.6. a 2 notch 1.9 hg is a little bit too thin for a 1.6 that requires a 3 notch, etc. you will notice ever so slightly worse cold starts, but its barely noticeable. i've run 15-20 psi boost on the 1.9 hg and its held up so far! :lol: