I have often searched for forums that have Wagon/Van enthusiasts, mostly without much luck.
Mitsubishi-forums.com has a sub-forum:
http://www.mitsubishi-forums.com/f74-ex ... -forum.htm
But it is pretty weak, almost no activity and when it happens, it is usually some "civilian" asking about his bone stock 1.8 FWD van.
However,
http://www.4Gtuner.com, from down under, has very active RVR sub-forum:
http://www.4gtuner.com/forum/52-rvr-spo ... technical/
Since they already have turbo 4G63s in their vans, their discussion tend to focus on modifications, repair and maintenance, rather than engine swaps. But still, nice to see a community that actually races these vans!
One of the reasons why they are so popular down under is because Mitsu really marketed these little vans in that part of the world. I checked out one classifieds website from NZ and found 90+ different RVR's for sale at the same time! Most of them were AWD and 10 were Turbos! Not bad for such a tiny country!
In US, you can barely find any 10 vans (FWD or AWD) between Ebay and Autotrader!