does octane boost ruin valves
Not normally. Why would do you ask
Increased octane reduces the rate of fuel burning so it should, if anything reduce the strain on valves.
No.
What is “octane boost”? To little octane in gas can blow a hole in a piston.
You should only increase the octane of gasoline if you can’t buy the required octane rating for your car. If your car requires premium gas, just buy it. If your car does not require premium (high octane) gas, don’t wase your money on it. Higher octane gas requires greater compression to ignite, but provides no more power than lower octane gas once it ignites.