If your getting the 3 horn setup that simulate train horns, (ones you install on big trucks) you better invest in a good size air tank.

im planning on hooking up a decent size air compressor in the back to work for them and to use to air up tires after the dunes

Just an FYI, those air horns use a lot of air. So, by the time your done "tootin" your horns, you may not have enough to fill tires up. I have seen these installed in commercial trucks and have seen the air pressure gauges for both tanks go down quick.

I don't plan on doing these thingss at the same time or incredibly often...

Installing a CTIS system would be awesome. Our big trucks in the AF had them (5 tons and 2 1/2 tons). They were sweet. They had 4 different settings. 1) Highway which had them at normal pressure. 2) Sand, which aired them down quite a bit. 3) I don't remember ahahaha. 4) Runflat. If we punctured a tire and it was losing air we could push that button and it would direct all spare air generated to keeping that tire inflated. Never got to use that button.

We actually have a holiday here in Canada so I'm off today, yippee! Needed a break anyway. Think I have to change a transmission in an ugly old Aztek tomorrow.

Change the car, do him a favor.

Yeah that'* about all that can be done with those God forsaken pieces of junk. They've gotta be the ugliest creation known to man kind to come from GM.

But they can go offroad!!

Only place off road I'd take one is to find a huge cliff, jump out and put a brick on the gas pedal and wave goodbye.