David,
What I've always done with my cars (carbureated and FI'd) here in 
Colorado is to advance the timing 1 degree for everything 1000 ft. above 
sea level.  They don't run worth a darn at the factory specs.  I've had 
my rabbit for the last 120,000 miles and have never had a problem.  It's 
currently getting 30s to 40s mpg in mixed city/highway with this setup.  
The van (81 Westy) gets around 22 on the highway with the same setup.
Jack

On Sat, 1 Jul 1995 dperry@miu.edu wrote:

> Later this summer, my 1980 Westy will be changing its homebase from the
> Prairie (alt. 700 ft.) to the High Plains of Wyoming (alt. 7000 ft.).  Are
> there any simple changes I can make in tuning it up that will make this
> fuel-injected, air-cooled van happier at high altitude?  People I've talked
> to so far seem to think that the fuel injection system automatically
> compensates for the lower density air and I simply have to live with a loss
> of performance at higher altitudes.  One person, who knows nothing about
> VWs, has suggested that I replace the air filter with one manufactured by K
> & N, if they make one for this engine, to decrease air-flow resistance. 
> Any Colorado van owners out there with real life suggestions on keeping a
> van happy on thin air?
> David   
> 
>