Hey mate
Sylvania (U.S.) manufacture high intensity bulbs for the Grand Cherokee, I'm not sure if they are available locally though. You would be able to get them via mail order without any problems. These bulbs get a huge rap on some U.S. Jeep forums.
Here's a link for one supplier:
http://www.mopartsracing.com/parts/lighting.html
Do a google search and shop around.
Drew