Tamiya only has two & three holes pistons, I suppose Chris Grainger use three holes pistons(not #3). It has three 1.1mm holes and 9.9mm in diameter. While Yokomo pistons have smaller diameter, 9.72mm. So the gap between piston and cylinder wall is quite big. I see a lot of yokomo set up from masami and other japennese drivers use yokomo #3 pistons with holes enlarge to 1.0mm. I try both piston last summer, Tamiya 3 holes pistons has a bit more grip but the differece was small. Tamiya pistons are a bit thinner, so you will need some thin motor shims to take up the gap. part # 53573.