I'm not 100% sure, but I think the Calmini kit just lifts the rear with springs and the front by cranking the torsion bars. So my answer would be no, you should just be able to install the kit. The question is, why Calmini? If you've been searching here, you'll find the consensus is that replacing the springs (usually with OME spings), rear shocks, and cranking the torsion bars is a better option than the Calmini kit.

Check out this article for more information about the Isuzu suspension: http://www.4x4wire.com/isuzu/tech/amigolift/?