Originally Posted by
jpatokal
You have a pretty unusual case there, since GMP's international flights are point-to-point shuttle services, and I doubt they have an international transit desk. It's a reasonably compact and efficient airport though, so my guess is that two hours should be fine, even if you need to go through immigration twice. (If your plane arrives on time, of course.)
I second that. You should be fine. GMP's international terminal is small and very efficient, so you should be able to get out and back in within a two hour window. You may get some looks/questions from the immigration officers on departure, though.