go to the auto parts store and pick up a pack of throttle return springs and fit one of them on the gas pedal arm and hook it to something under the dash solid. Adjust slack in the spring so at half throttle or wherever it starts pulling the spring. This is the easiest way to give yourself a reminder not to go past that point. If you need full throttle though a bit of extra spring tension on the last half of the pedal travel is no big deal.
I've done this and it works very well....no safety issues either. I used some wire and an extra spring set up so that at a certain point the extra spring was in the mix.
Just be sure you have no binding of the throttle though.
Leading the perpetually ignorant and uninformed into the light of scientific knowledge. Did I really say that?
a new policy....I intend to ignore the nescient...a waste of time and energy.