I don't chop myself but a good friend of mine has a 2 row deere chopper he pulls behind a 4440 (dyno'ed 170hp). Normally its no problem at all for it. 3 years ago (last time he chopped) A1 was not slow enough for the tractor. You had to ride teh clutch ever now and then or it would stall the tractor. The corn was three feet over the top of the cab though.