dont do this, the 20 amp breaker is so any load higher than 20amp will break the circuit. if you put a 25 amp in then you may blow everthing else including the lights. what else do you have on this particular circuit? as you havent said. If there are other appliances on the circuit consider shutting them down using the saw only. by the way all the other answers are ok.How many amps is the saw? add all the appliances amps on the circuit up and see what is being drawn at the same time, you may be unpleasanly surprised.