since i havent got mine yet i can only quote on what i have read, but form all that i have gotten this...
you should order the size up from what fits you so say if your 9stone the m60 (9.44stone) would fit you so you should get the m70 (11stone) this will keep you from bottoming out and might give you better bounce.
they sqweek for a bit when you first get them to sort this just spray some WD40 onto all moving parts.
also the spings need 'breaking in' this takes at most 2 weeks if they are not used much when they have been broken in they bounce much higher.
when you first get your PJs you should rap the springs with 2 layers of electrical tape then a inner tube (cut it the the size of the spring and rap it around) then you rap another few layers of electrical tape around them this keeps the springs safe everyone does it and its essential.
for the feet they run out fastish so you should make some tire socks this video will show you how to make them
http://www.xtremeimportz.com/Powerizer_Instructional_Videos.html it is the second one down.
and it should take bout 10 - 30 mins for you to be able to stand and walk.
i hope all this helps you out happy bocking. =]
Dave! x