I bought a unit from HotRod Air 3 or 4 years ago because they got good reviews at the time, the dimensions of their unit fit my application better and the price was a little bit cheaper than Vintage Air. I still don't have the car on the road yet and I just learned HotRod Air has bit the dirt with the economy but hopefully, everything will go together fine and the unit will work properly. I haven't heard anything good about Southern Air.