IIRC people fitting intercoolers to VW 1.6 TDs saw intake temps drop about 150*f under load. I'd be interested to see what the stock intake temps are on a mercedes as well. Using the location the overboost sensor normally screws into could be an excellent probe-point.

-Jason

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1991 350SDL. 222,222 miles (new motor @ 150,000). Transmission time again...

2012 Passat TDI. 23,000 miles. More space, power, and fuel economy than the Benz
1999 Jetta TDI. 284,000 miles.
1992 Jetta ECOdiesel. 156,000 miles. 1 of 48. Sold.
1991 Jetta ECOdiesel. 430,000 miles. 1 of 700. Sold to VeeDubTDI, totaled in front of our house