I've been thinking what will happen if I replace a 136.5 mm valve with a 130 mm valve (intake and exhaust valves):
Compression ratios will surely go down but what will happen with the following?

1. hp & torque band (will it adjust dramatically? will it widen or shorten?)
2. starting characteristics (cold)
3. operating temperature (this will go down for sure but how drastic?)
4. what else?
5. do i need to change the valve springs too?

Theoretically higher CRs will result to higher efficiencies but the pressure will surely go up too. same goes with the operating temperatures.

waiting for your replies everybody. thanks