LOL… when I go looking at cars now I always look first to see where and how I could mount a tank and horns. Priorities priorities 
2007 GX470
Will use nitrogen and surge tank.
The Nathan P124, older castings, is a very pretty horn with its A major triad (1st inversion, tonic on top) You should be able to disassemble the bells from the bracket and pipe them separately…I thought I saw a kit on fleaBay which enabled you to do so.
I’ve got exactly that kit from realtrainhorns.net, but they are still impossible to fit in. I’ve actually got a new cast P124; for some reason I prefer the sound of it over the old cast horn. I’m going to keep them for some possible future use, but this car is probably going to have to live with shockers.
Alright, so here are the shockers all mounted and ready to go. These are much easier because of their light weight and better dimensions. I still wish that Hornblasters would sell individual bells tuned to specific notes along the musical scale so that I could create the sound I want. But anyways, here’s the pic of them mounted behind my bumper:
Well, my car has been in the body shop because of an accident (not my fault), but I have it back so I have been working on my onboard air setup over the holidays. I have a 4 gallon aluminum tank and 2 air zenith OB2s running at 200 PSI. I just built a manifold setup around my high CFM regulator, with the pressure switch, blowoff valve, and 2 pressure transducers on the high side, and a 1/4 inch quick connect and 2 additional pressure transducers on the low side.
I’m going to have a dual digital pressure readout (high and low side) for the front of the car and another for the rear. (I’m building it up for future expansion to a larger vehicle or more tanks.) I’m also setting up some fail-safes to prevent issues like valves sticking and relays welding. For the relays, I will be using the stock AZ relays in series with a high amp solenoid, and for the sticking valves I will be doing the same - 2 solenoids in series. Low side will be set for 120 PSI.
I’m using all aluminum -8 AN Aeroquip fittings and 1/2 inch aluminum tube. Here’s the manifold that I have been working on over the weekend:
Compressors are on the other side of the board - this will be going in my spare tire hole:
Happy honking new year!
Man… that’s got to be inspired by that monstrosity Ear2Ear was working on 
Sterling work with the pipes and fittings though.
Holy transducer Batman!
Now that I think about it, I wonder if one tranducer would run 2 displays? I didn’t even consider that possibility, which would have made it simpler and easier to create.
Wow! 
nice job!