Where is the best place to install the horns on a 2007 Ridgeline
Uhmm… what horns are you referring to?
Welcome to the forum by the way.
I just got a set of HornBlasters Conductor’s Special 228VX Train Horn Kit where can I put this on my 2007 RidgeLine
Nice choice - the beauty about the Shockers is that you’re not stuck with having to put them all in the one spot which makes it a lot easier during the install. I’m not familiar with the Ridgeline, but had a look at some photos. I’d be surprised if you couldn’t find room under the front bumper or behind the grill. You may have to remove some paneling to find the best spots though. Don’t worry about running out of tubing on your air line since you can always buy some more very cheaply.
The more challenging part is finding a good location for the tank and compressor. Are you going to hide it under the tray or inside a toolbox perhaps?
If you want to get inspiration on some ideas, have a peek at the HB install gallery:
http://www.hornblasters.com/installs/class/?train_horns_on_trucks
Maybe someone here will chime in who’s had a similar vehicle. Apart from that - just go for it and ask questions if you get stuck or not sure about stuff. Looking forward to some install pics and a vid 
Welcome to the forums.
You can look in the install section for trucks to get some ideas. But mostly, you just have to crawl under the vehicle and start holding the horns in different locations. Under the bed, along the frame rails, behind the front bumper/grill, etc. You’ll just have to see where they fit without hanging down too far.
I can’t suggest any more places so Welcome to the forum.