If you want kick without an amp, drill a hole in the roof of the Jeep, get a decent sized antenna like a Sirio Performer 5000 and install it using a fixed mount. Go to www.k0bg.com, read the pages on mounting, grounding, bonding etc (especially bonding if nothing else) and install your antenna system as per the recommendations on that site.
The performance you'll gain from having a good antenna with a proper installation as efficient as it can get will see you put out a signal with 5-10W as strong or maybe stronger than someone running 100W into a crappy antenna or a good antenna installed poorly with no real ground plane.
The performance you'll gain from having a good antenna with a proper installation as efficient as it can get will see you put out a signal with 5-10W as strong or maybe stronger than someone running 100W into a crappy antenna or a good antenna installed poorly with no real ground plane.