Two answers to that question:1. I hire my Decathlon out and I expect the pilots to adhere strictly to the rpm limit of 2700 - I suggest they keep the rpm around 2500 to give a bit of margin and they soon learn to judge rpm by the sound.
2. I flew Guido Zuccoli's Pitts once and he told me not to throttle back at all - I had to force myself to disregard the tacho. If you've ever heard a Pitts wind up at an airshow it could easily be doing 3500 rpm or so. I never liked to abuse my own engine that much and the extra thrust wasn't really noticeable. I'd take our own Pitts/Laser to 3000.
Until you can judge the rpm by sound, determine what airspeed results in your max rpm at full throttle - so that anytime below that airspeed you can use full throttle.
Regards,
Dave Pilkington