i just traded out some work for this 1990 b16 head. on the Lf above and in between the #1 and #2 cylinder the is a ground off spot with the indentations that appear to be A.P.D with OC 231 below that. if anybody has any idea who may have done the work to it, i would like to no. thanks i will try to get some pics of the combustion camber work and the spot were the head has been punch marked

 

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