Just added Firestone bags to our 2009 Tacoma. Not sure if the brackets are the same for your bags, but I aimed the brass elbows towards the rear bumper ends...that is, if the front of the truck is north, the passenger side points SE and the driver's side points SW. The air lines run along the inside of the frame to the rear bumper (the air inlets didn't fit at the license plate, so I utilized some holes on the bottom of the bumper).
As you can see in the photo above, the guy who did the installation pointed them in towards the center. I turned the one near the exhaust pipe toward the rear, left the other one alone. I have to say, even with my shell on and stuff in the back and only 5 psi of air, they sure jack the back of the truck up. The ride to Reno with nothing in the back is going to be interesting...