Yes you need special permission. They don't simply allow you to pass the check points. Put it simply, yea you can't go through the checkpoints. I've tried it before.

you have higher chances of reaching gohtong jaya via ulu yam.. if you start from genting sempah... there might be a chance the guards at genting sempah will stop you already..

oh, and... don't do it on weekends... more likely to be told to go u-turn and go back...
there is no permission lar... u just try to get through the guards and if they let you, they let you go lar... if they don't allow.. then it's a no go....

pump up to pressure is one thing... ease of pumping, how many stroke it takes is the other...

no point recommending cos it might not be available there... the birzman zacoo pumps are not bad...else, i jus buy topeak... since now rodalink has service kits... i don't need to worry about it crapping out...
then, how you go back up?

there is nothing special about GH lar.. to me at least.. and the descend is actually more worrying because if you are familiar with the roads... the top part is zigzagging all the way down.... and it is hard for cars to see a bike coming round a corner as the roads slope down as they turn in... a bit dangerous if you are not careful...

tat is until u clear the temple... then the roads straight straightening out and is more open....