Did they/you bleed the lifters?
If not they may not be letting the valves close all the way and causing them to hit the top of the piston.

Check out this link, go about halfway down where it says "Priming/Draining Lash Adjusters"

http://www.dsmtuners.com/forums/articles-engine-fuel/265060-how-replace-lash-adjusters-lifters.html


If the head is already torqued down onto the headgasket you can just remove the cams to do this so you dont have to buy another headgasket too.

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I used to have a 420A...


'92 TSi AWD

11.8 @ 119mph
470awhp 405 ft/lb torque
30psi on E85 w/ Borg Warner S256 Turbo

My DSM Registry: http://www.dsmregistry.com/166