I have the 400P and it kicks ass. It doesn't really take that long to cool down, works fast and fits under the back seat of my JT (with the plastic cargo bins).
I had a power wagon and rubicon wrangler, both sucked on the highway, both kicked ASS off the highway and both broke down last summer. I combined to the jeep truck in Mojave. Love it and couldn't be happier.
here's how much clearance I had parking my PW at the Safeco Field garage.
Guys I just installed this weekend. Covered in bruises on my back from the fricking seat rails... I'm not a small guy. For part of it I laid upside down on the seat folded all the way down. Anyways, I don't have any way to test it now until I get the rental trailer at the end of the month...