Any math majors here? OHC head milled.....

The slack is not the issue as its on the trailing side, the tension side does not change. Shims are available but they are only .020". The mill limit on these heads is only .20mm! This machine shop took 1.7mm off this head...Great for a compression boost, not so great if it barely passed NOx smog once before with the uncut head. IIRC the stock compression ratio is 8.6:1, not that high to begin with.