That makes sense. One more question.
What does manifold pressure indicate exactly? In other words I want to think of the throttle on the plane just as I would the throttle on a vehicle. So if I increase throttle, engine rpm increases and the car goes faster assuming no downshift occurs. In a turbocharged engine the intake pressure also increases with rpm increase but it isn't linear. So on my desiel truck (manual...no shifts) I can give lots of throttle and see the pressure really increase but the rpm increases bit slower....hard acceleration gives a large spike in pressure, moderate accel gives less of a pressure spike but in both cases pressure lowers and settles down once the acceleration (or heavier workload such as climbing a hill) is over.
When I look at the manifold setting on the plane I tend to see that as a 1 to 1 relation with the throttle or how much fuel I'm giving the engine. Is the manifold pressure a measure of intake manifold pressure? At full throttle are we running around at max allowed (governed) manifold pressure? For example a gen 3 5.9l cummins had a factory max allowable pressure of 30 psi. You can ask all ya want of the engine, it will not (under factory settings) give more than 30 psi. With decreased workload (pitch or rpm setting) on the engine then the pressure reduces..similar to my truck? Why do our manifold pressures not spike under heavier workload such as in a climb vs diving? Does the prop go through a gearbox....or is it bolted directly to the engine crankshaft?
That's actually alot of questions..sorry lol. I am just curious as I really don't have a good understanding of this stuff and I find it interesting. Sorry for the truck analogy but that is something that I understand and sort of how I try to understand the plane engines. 
Zaphod
I'll break it into two parts and hope I don't confound things.
First, in reference to gearboxes with your truck and planes. Most prop planes have a single/single-set gear reduction. From memory, but I would need to look it up to be certain (and coincidently I will be looking those sections up hopefuly soon when I get three prop blades back from Texas anydaynowortwoweeks...
), a Packard built Merlin mustang has a 1:2 fixed ration with the prop, meaning for every two full circular roations of the prop, then engine goes through one cycle/rotation.... prop strikes are very bad because at best you maybe bend a prop and sheared some of the reduction gearing before bending some rods or worse, and on the opposite side of the spectrum you can overspeed in a steep dive - unpleasantries avoided by your land-loving truck thanks to neutral and the ability to shift up to 5/6 gear while pushing mach 75+ on the highway.
Manifold pressure... uh-boy, lets give it a try.... In a nutshell, it's measuring atmospheric/air vaccum "pressure" the engine is intaking/consuming/sucking-into-the-carb. Mind you, with engine off on the ground you'll get a reading of the neutral/natural-atmospheric/barometric pressure (~28.6" or whatever the weatherman says it is at the moment). While at idle, you're starving an engine of something to "idle" it back (usualy air with the throttle back), so normal/average reading at idle would be ~10-15". Throttle is one of three (the other two being prop pitch control and your fuel mixture control) controls and governs how much air/atmosphere you're letting into the engine - MP tells you how much air your throttle setting is letting into the engine which can vary with a number of circumstances, so
it is not accurate to
describe it as a "throttle position indicator".... Confusing enough yet???.... here's a great in debth explanation:
http://www.askacfi.com/421/what-is-manifold-pressure.htmTake the good information provided by Vinkman and it starts to make sence why you wont get much more or less than mid 30"s and how the german 0.9/1.0/1.1 ata converts.... now, I msut admit, clueless am I about how precisely the british boost system works but I'm assuming it has something to do with their metric "bars" for pressure measurements.
