The european MP3 xxx is usually sold with the Michelin Gold Standard (or Pirelli GTS 23/24).
Except the 125 RL and 250 RL, they are all heavier than the Xciting 500.
MP3 LT 250 (wife): 236kg, Xciting 500 (mine): 230kg. (MP3 LT 400: 262kg.)
I just went outside to my wife's MP3, but I couldn't find a max.pressure on her MGS tires. Perhaps very small printed, but now it's dark and snowing.
The manual says up to 2.6 Bar rear tire pressure (for the 400cc with pillion rider), which is nearly 38 psi.
Although the dimensions are slightly different, 140/60-14 or 140/70-14 for the MP3, I can't imagine the 150/70-14 would be rated much lower. 36 PSI should be ok.
But another thing: I do not recommend these tires. In the cold and wet, even worse on snow, they don't provide grip. I had enough experience with them the last 2 months.
Poll in a german MP3 forum:
Question: "Recommended tires?"
1) Heidenau - 28 votes, 64%
2) Pirelli - 11 votes, 25%
3) Michelin - 3 votes, 7%
4) other - 2 votes, 5%