I researched every thread I could find. There are three rear mounted options each with its pros and cons
1) horizontal under the trunk floor - fairly easy to do with minimal car cutting. Works with a good fan.
2) in the right rear fender ala Perry - no personal experience but I really think this is a great way to do it - min car cutting, clean and effective.
3) under the rear engine cover - really like this setup as it requires no fan and no car cutting. Some think there is a net zero improvement in cooling efficiency. I don’t agree. And it is endorsed by Henry Schmidt :-)
I chose 1) with a fan and an elaborate duct/plenum that worked very well and I figured a way to do it with zero car cutting. (Here is a thread
http://www.914world.com/bbs2/index.php?sho...=314444&hl= ). I did not include a pressure relief/thermostat and blew the cooler on a very cold day due to overpressuring the cooler on start up. I abandoned the whole thing and returned to stock. No cooler Works fine for street driving. 2.4S motor.
All three take about the same dollars and work. Doing it over I would probably do 3). Probably simplest, cheapest as it requires no fan or thermostatic switch, and fits well.
Takes some thought and engineering to do iany of the three right to includie cold start pressure relief.