I dont know if this has been asked before but has anyone used any fuel saver devices on any kombis and if so which ones work and how good are they.
Or are they just money wasters?

in my expert opinion and big mouthedness, they're a crock
your best fuel saver is a tune-up, new points, the best carbies you can afford, and a light right foot

thanks for your opinion i really need all the help i can get before i get my first kombi
anyways anyone else with advice or experience with this that could help
and what other ways are good for fuel saving in a bus?

If they were any good, We all would be using them and saving money... I have never heard anyone say they had found one that works....
Many people used ProMar fuel additive about 10 years ago, many people said it was a great product, with engines idling better etc....

There used to be a device that used a progressive spring on the accelerator (and a more expensive one that had a little "shock-absorber" - at least it looked cool) that worked - you couldn't drive fast!

As for the so-called catalytic devices - don't you think vehicle manufacturers would use them if they worked (they don't) ? Fuel economy is a major sales feature in all vehicles.