[solarguy]

My 04 tdi wagon (240K miles) gets the best fuel economy if I avoid using the turbo. So I accelerate gently and shift at around 2,000 rpm.

Moving to a bigger turbo will do nothing to improve your fuel economy.

Now, if you want to increase your horsepower by 40 or 50% and still break 40 mpg, a little bigger turbo makes a lot of sense.


Doubtful that you need a new intercooler unless it's leaking. You would hear it, and likely smell it.