Basically after some info, my series 2 has a 2ltr zvh engine in which i built usuing standard zetec pistons and a 1.5mm de-comp plate its set at just under a bar of boost and a reasonable bit of advance on the dizzy(think i need and adjustable pulley to get it spot on) and it goes spot on pulls nice all the way through the revs, but we built one for a friend of mine but instead of using a de-comp plate he skimmed the standard zetec pistons by 1mm and when we try adjusting his boost and timing it just pinks is this because the compression is still to high as the rest is set the same as mine ?