Getting a thicker HG only
lowers the compression ratio, it doesn’t net you any more horse power. However if you have the supporting upgrades(fuel, turbo, ect.) it allows you to run more boost without entering detonation. Were talking 20+ psi before you even have to start thinking about that. The down side to lowering the compression ratio is that you decrease the off boost responsiveness of the motor.
You need a happy median between detonation prevention and response of the motor. The stock HG thickness provides this balance. The thicker HG is only to compensate for the material you have to shave of the head/block for them to be straight again, and return the compression ratio to normal.
edited: because of dyslexia