>How does one gain an advantage by replacing my 1.9L or 2.0L with a 1.8L?

If you want to go fast in a vanagon you need very high rpms.  These
smaller engines are CAPABLE of running at higher rpms with more horsepower
than the wasserboxer.  However, one of the reasons i would never consider
a vanagon engine conversion is that NONE of these engines are designed to
run at very high rpm's (4500+) for long periods like they will be when
connected to a vanagon transmission and driven on the freeway at 65+ mph.
Of special concern are the TDI's.  The diesels are really made for low end
torque and the transmissions that use them are geared appropriatly.  I
asked overland parts who used to offer a TDI conversion for the vanagon
and they confirmed that the TDI in a vanagon with stock transmission is'nt
going to make you go any faster.

Andrew Fox