ok, port velocity and shape are everything, port speed fills the cylinder, not valve size!! as for power, we have tested 2.02 and 1.88 valves on real flow bench. the 1.88 has more port velocity, vs the 2.02. flow is close. the X head was designed for 2.02 valve, the others were designed for 1.88 valve. now, to compare power, in stockers, the 1.88 headed engines are as fast as 2.02 headed engines. some exceptions are there. Chevrolet, went to 2.02 valves years ago. it was a marketing ploy! we tested a chev head with 1.94 and then he opened up bowl , installed 2.02 valve and retested, flow and velocity loss. imagine that!! valve type and seat angles are important to flow gains. I realize you can't brag on 1.88 valves. 2.02 , you can. lol. BTW, a 1.88 valve 340 runs to 7300 rpm in traps, doesn't lose power. 283 chev super stockers, with 1.75 valves run 9200 RPM. no power loss.
