I wears wondering I put a newer turbo on her with a faster spool on, it would improve the mileage.

Probably not. I improved the mileage on my Dodge PU by going to a larger turbo that doesn't make boost until you need it. The stocker would make 1# with the engine idling in gear, the replacement is making 2-3 # cruising at 65 MPH. If you want more MPG, you have to lower the drive pressure, which is exactly what I did. IMO, you are already at the top of the fuel economy available for that car.

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'83 300D, 126K miles.