Ridin' Green, you are going to force me to read the owners manual
I just ordered the throttle shaft for the FX730V which should add 3HP to the FX651V that is in my mower. 15% extra power should make a difference. It will be under $40 dollars for this conversion to be the same as a Z920A It sure beats the $1,400 JD wants to go to the Z920A.
The info that led me to this is here http://www.lawnsite.com/showthread.php?t=317558
and I ordered the parts here http://www.partstree.com/parts/?lc=k...99907-61990080
Part # 16041-7052 $25.00 (I ordered some extra throttle plate screws)
If my new mower won't do the job I can always use the HX20!