Love the Blaster forum reading it a lot , I started to rebuild my blaster had low compression 90 psi , took the head and jug off , jug looked good had it honed out and measured the measurements are top 67.41 , mid 67.44 , bottom 67.5 , my question is I was looking on ebay for pistons and what size do I get 67.5 ? or 67.0 was thining of getting this one http://www.ebay.com/itm/381001219348?_trksid=p2060778.m1438.l2649&ssPageName=STRK:MEBIDX:IT