I have this tire repair kit that works great. I used to carry it on my motorcycle and it saved my butt a few times in the middle of nowhere. I used it on the Evo also after getting a screw in a tire.
Check it out, you could even get rid of the spare tire and jack and save quite a bit of weight. Of course if you get a slash in the tire your screwed They say not to run the tire over 100mph after plugging. Well I've never had one of these plugs fail. The mushroom shaped plugs keep them from coming out. The plugged tire on my Evo doesn't lose any air.

http://www.teamiguana.com/Reviews/StopNGo/page2.htm

http://www.stopngo.com/plugger.htm

Get the one with the gun. Also buy one of those plug in tire pumps. This is a great product!