I Know Mark thinks 2.15 is optimum with a standard Block height & his stroker has slightly changed rods & a pin moved up the piston. The exact dimension are selected to get the optimum angles, please dont ask what that is because I dont understand it. However it means bespoked Crank, Rods & pistons. Although not cheap its the preparation of the Block to withstand the Big Horsepwer that can be achieved with this combo that costs the money.