I am looking to replace the motor on my 52 Toro Z-Master. Right now I have 19hp which still runs but is tired, it has about 1800 something hrs on it. Has anyone ever replaced the 19hp with a 21-23hp? Did it make a big difference? I always thought it was a bit under powered. Also would and older 25hp fit on the mower or would that be too big? Thanks!