Our governor will hold speed in relation to set position as a tractor governor will. I have wired my cruise control system to pull and hold the the throttle lever, using the existing cruise control hardware. I have disconnected nothing. I have full function of the cruise control. The existing vacuum pot driving the cruise will hold the engine at a set idle speed anywhere from low idle to high idle, and it will control speed on the road but not as well due to the designed droop in the governor. The old Ford 6. 9 and 7. 3 with the Stanadyne DB2 pump was not a full range governor and you cannot hold speed with constant throttle position. There are 2 ways to verify your governor type. 1 try holding it at half throttle and see if you makehalf speed, or about 2000 rpm. 2. Especially with manual trans (no slippage) accelerate slowly, you will notice that you must gradually and uniformily depress the pedal as speed increases. More pedal, more speed.
Droop is required in every governor to maintain stability. Zero droop would mean a request for full fuel with only a drop of 1 rpm from the set point. The engine would overshoot and then the governor would request zero fuel. the result is the engine will hopelessly hunt up and down. Droop stabilizes the governor and speed of the engine. When the speed climbs close to the set point the fuel is reduced gradually so as not to overshoot, same if speed is dropping towards a set point, then fuel is gradually added as the set point is approached. Why mention this? Because of droop, there is some vagueness to the feel of the pedal and response of the engine. A lot of droop will start to feel like it is not full range governed.
The cruise control of any vehicle is a road speed governor, and road speed will vary slightly over hills due to droop in the cruise control. some more than others.
We defeat the droop at top end with the governor spring kits, or, more accurately take it above the operating point so it is out of the picture.
There are several reasons why we de fuel at higher speeds. The fuel plate will influence rack position as a function of rpm, most plates defueling at higher speeds. The AFC will defuel with lower boost. And the governor will defuel as it approaches the high idle set point due to droop.
The B5. 9 is rated to 56,000 lb gross vehicle weight in comercial use on hiway. The fuel plate allows tailoring of the HP and torque curves to give us the towability that the engine is famous for. In heavy duty applications increasing torque and even increasing HP as rpm drops, is what allows us to top hills heavily loaded without down shifting or loosing much speed. That is precisely why the plate is needed to add fuel at decreasing rpms. When you use this engine to it's limit towing, those plates are necessary for drivability and economy. For hot rodding empty with short spurts empty, and racing, none of that is important. Only in heavy towing will the engines power be used continously, and then the plates help set some limits that are reasonable to get the long life.
That is why the #11 plate is so good towing. It adds a mountain of fuel (torque) as speed drops and lets us pull grades without dropping speed much or downshifting. It also is reasonable in power produced so as not to decrease the engine life substantially under heavy constant use. Engines with peak torque low in the rpm band and decreasing torque with increasing rpm from the peak are the best towing engines.
I guess I am only making a case for why most of us should leave the plate in, and use a plate that matches our use of the vehicle.
Doug Rees
Attention: TDR Forum Junkies 
There is a type of govenor that reacts to rpm increase and decrease. It is called a constant speed govenor and they are on most tractors. 
). I am crummy at typing what I am thinking. 
And now is sliding back to the dark side:{ And to make matters worse... . I am no closer to understanding the P7100 than when this thread started
-not that everyone hasn't tried. I am one of those that need to see a dissassembled pump with my own eyes to begin to even has a slight grasp of this subject. 
I'm actually running without a governor now (above 1200 rpm). 
