Miata 1.8 lts 84mm(+1)/ 4032/ Forged piston/Comp. height 30.7mm / -4cc Dish /20mm pin Off Center/ Rings 1, 1.2, 2.8mm. /Valve pocket depth Int.: 4.4mm (diam 36.5mm) Exh: 3.8mm (diam 31mm) /C.R.: 9:1..560HP/ 30 psi