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

Theres little gain with a 2.02 valve in a stock unported head. Once you start porting the head, the difference that was only a few cfm starts to get wider. By the time a full port comes into play, they are very worth while.

The loss in velocity is what ou812 is talking about in guiding you (Or anyone) towards a smaller valve. Hi velocity is key in making power. It is more important than a big valve. This defiys the old thinking of bigger is better. Mostly because the old way was easier to do, AKA cheaper. However the bennift of a better working engine, AKA effeciencey..(humm, SP!) is well worth it over the bigger is better thought pattern.

Most people here do not build an engine that simpley skips over the entire power band down low and use converters that flash @ 3500+ RPM's unless there drag racing. In this line of thought, track only, a smaller valve is probably not a good choice, even more so when going on the cheap.

Any builder/head man worth there salt would guide you in this manor like ou812 is trying to do.

Valvebounce, in forced indution, it will matter little since your forcing the air past the valve, under pressure. Build dependent, I would still look at the valve size as a major player in what is going to go on in the engine.