mcconnell,

 Have you used the tractor yet?  Are you sure you need more power?  I have a 08 Steiger 335.  It lugs nicely on the NH3 bar.  It runs better than I thought it would. 

 Having said that, I am 90% sure mine had a chip on it from the previous owner.  The "clip" on the side of the fuel rail has been broken.  After 250 hours I can't tell the tractor has any problems from the chip.

My father has a 385, yes if has more power.  But it does not "turn" as nice as mine, or run down 30" rows if you need it to.  I plant with mine, apply NH3 in 30" rows, and will use it for fall tillage if I ever get the chance again!  I will chip it if needed.  A chipped 335 is more versitle than a stock 385/435.