Hi Jay,
I second Pete's observation.
It's a little presumptuous of me to speak up on this topic, since I am completely new to tractors myself, ...but I've been studying hard at TBN University for the last year-and-a-half or so. /w3tcompact/icons/wink.gif
Based on what I think I've learned here, I'd bet that the single thing that would most improve your tractor's performance would be to train the operator to a high level-of-competence.
By comparison, any "hot-rodding" tips would be wasted effort, ...if you can't get the most out of what you've got, how will getting "more" help?
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Using the rig will let you know about any areas which could stand a little improvement, THEN you can decide what to put (more of)your time and
money into.
Good luck, and happy tractorin'!
/w3tcompact/icons/smile.gif Larry