snip:
"""do custom mods ........ increase or at least not decrease value?""

You just bought a 19 year old van.  Why are you worried about resale value?
If you keep the van for "some time", it will be even older, thus even less
valuable.  Vehicles with 200,000 miles on them don't have ANY value, according to
some.  (ask your insurance agent)  If you are planning on selling it, keep the
mods small and don't put any big money into it.  Remember, it is 19 years
old.  Keep it running and enjoy it.

If you do sell it in the future, it will be to one of us bozos, so we will
understand the modifications if you document them well.

Bill Marshall
85 GL Tiico "Pandora's Box"
Aurora, IL