how much do you gain with 202s over 188S?

I don't think you will pick up much if anything on the top end and possibly loose bottom end if you don't open the bowl up and clean the ports up to take advantage of it. And like implied above if its a mild build you might not need that bigger valve.

I think mopar put the 2.02 valves in there so they can say their valves are as big as the chevy valves. The bowl and port really need some work to take advantage of it.