well my cylinder head is already shaved 0,4 but due to a bad gasket i need to schim it again.at 0,4 i didnt have any issues with lower chain,tensioner noisy motor etc.the engine is cg13 and i know that it has 9,5-1 compression and at 0,5 it will propably reach 10,3 to 10,2-1(i will do the maths...