My friend has an 04 jetta diesel and he wants to know some cheap or good ways to get better mileage and power. what are ya'lls ideas,
Thanx, Zach

 

If 04 is commonrail, you can do quite a bit with a tuner. Auto or manual?
If its pre commonrail, nozzles first then rocketchip tuning.

 

The stock intercooler is a bit small. He will or has recognized already a power lack during the hot summer months.
There are plenty of huge upgrade intercoolers available to provide better air cooling.
eg.: Forge

More air + fuel = more power.