I bought a 77 John Deere 4430 last fall from the original owner with 5400hrs on it. When I bought it, I asked the old feller if the injection pump had ever been tinkered with. He said no, never needed any more power. Did some chisel plowing with it last fall and noticed it was quite a bit peppier than my 4320, so when I had the 4430 at a buddies place getting some minor things fixed, I had him put it on a dyno. Put out 160hp. Nebraska says it's rated at 125? Everything is original on this tractor. I could see hp changing a little from tractor to tractor, but this seems a little extreme. Just looking for some thoughts on why it'd be like this. Are they always a little hotter than rated? He's dyno'ed some other tractors for me and all have been around the rated power. Looking to make a little discussion I guess.