4G63 (EVO.IV - VII) HEAD GASKET BORE THICKNESS PART NO. MSRP (USD) MATERIAL STRUCTURE Φ86.5 1.2mm 1352865121 $290.00 Metal Super Grommet 1.5mm 1352865151 1.8mm 1352865181 Sample Compression Ratio ● 4G63 (EVO IV - VII) Gasket ø86.0 Piston STD ø85.0 PistonTOMEI ø85.5　2.0 PistonTOMEI ø85.5　2.2 1.0mm approx. 8.6 approx. 9.0 approx. 8.4mm 1.2mm approx. 8.5 approx. 8.9 approx. 8.3mm Values of the sample compression ratios are calculated out based on the factory spec data. Adjustment of the compression ratio must be based on the measurement of the actual engine.