Currently I am not at home (holidays) and I cannot recall what the pitch Up or Down I felt when giving speedbrake. If there was any, it was little pitch effect. As always, try these first at altitude.
Due to several circumstances I did not fly the MB a lot, neither recently (over a Year now).
I am planning to redo the innards of the MB first this winter before reflying it. Not that there are problems, but when I built my last jet (Pirotti Tuono) it was the first time I really spent enough time getting all electrics and pneumatics NEATLY inside. Now looking at my MB I feel more ore less embarrassed when looking inside.
I have a building report on my Tuono http://www.flytobiggs.com/index.php?...gen&Itemid=137
Sorry, only in Dutch, but lots of piccies.
Now with a lot more experience with all systems I have a better idea of how and where installing components, plus I might opt again for mechanical air valves, in hindsight (and my new Tuono has them also) I prefer the mechanical valves like the ones from UP over the electric ones.

I see, I have the mains on 14mm with oil, then 10 bar. The nose is difficult, my settings were too high, one friend of mine uses lower pressures, as the MB needs to sit nose low.

Of course You are familiar with higher true air speeds due to the elevation at Jo'burg....