Is that a 5 gallon? The 3 gallons are really small. I did two 3 gallons, you can mount a compressor at any angle and that bracket just un bolts from the compressor body and you can bolt it on any side. I was able to lay the tanks on their sides, and same witht eh compressors, I have big valves so I put them down in the spare tire well. If you click on the link below you can check it out, I dont want to hijack our build thread with a picture of my setup. It works pretty good, floor is above level with the lower trunk trim/latch.
Whats under that carpet? There seems to be a crap load of empty space. Two smaller tanks would probably fit beter, that stupid center hump is a pain in the ass. I don't think there is anything in there either, maybe evap but I doubt it. I would just pull the carpet and all of that and store it somewhere, someone should make a donut tank the size of a spare tire. HA!
I know there are 4 gallon tanks to that are skinny like the 3 gallon. The problem with the 3 gallon is that have a port on the side of it, so you have to factor in the plug height, which I just ended up cutting a hole in the wood floor I made, that allowed the tank to sit as low as possible in my frame. You can see from the pictures of my build.
ANyway looks good cant' wait to see it finished! Looks good, can't wait to see the final product! http://****************.com/smile/emthup.gif