Hey Dude, I did a little reading on the subject of the pistons, and you can put a kit on the A3 but have to machine (drill)out the top rod, it is smaller rist pin brg there. I am having a hell of a time with the advancing the timing project I started....specialized parts needed and had no luck finding (offset moon keys) I can mabe get them made, or for the Tomos, get new keyways cut...not expensive....just a crapshoot one first motor! But I do have a extra A5 motor to melt...HA! Good Luck.. Doug D.