There is a bit of a back story here I should share with you. I ordered my 2012 5065 E in the spring of 2012. At the same time my friend was looking at new tractors. When I brought my tractor home he looked it over and drove it and liked it. We had a JD dealer which was going out of business about 20 miles north of us and they had a 5045E in stock they were willing to discount heavily to move it out. My friend made a deal with the dealer and bought the 5045E. After using the tractor a short while he decided he would like a little more horsepower as he was using it in his woods pulling logs, loading the bucket full with firewood and plowing his steep driveway.
My friend retired a short while ago from our state dept. of transportation as a heavy vehicle mechanic. When it comes to diesel engines he knows them inside and out. After doing his homework he ordered everything he would need to convert his 5045 engine to a 5065 engine. He did this in his own garage in a weekend.
Between the discount he got on his tractor and the fact he did all the work himself he ended up with a higher HP tractor and still saved a few thousand dollars. He has nearly 1000 hours on the tractor now and hasn't had a lick of problems with it except for a bad starter and having to replace the original battery. I have had to replace my starter and battery as well.
At the time we bought our tractors we knew more emission controls were going to be added on upcoming year tractors. We weren't interested in all the headaches involved if we could avoid it.
I personally don't know enough about this particular model to offer help. But I am sure there is a way, however you may come out dollars ahead by just trading up. Depending on where you are at, 5 Series are more plentiful used than subcompacts in some markets.
But I like the post above. If its not a computer controlled engine, swapping injectors, adding fuel pressure and turbos/intercoolers will work, think like those guys that do tractor pulls. Doesn't sound real practical for a field tractor to me though, I am pretty sure the old 70s and early 80s tractors had options for juicing them up, a 2012... I don't know.
Simple. Change the injectors, injector pump and the turbo to 5065 parts. I have a friend who did exactly that and his 5045 runs as good as my 5065. How much mowing do you have to do that you think you need a Batwing mower?