Sharan: Transmission Problems After Chip Tuning?

Hello, I bought a VW Sharan with a 90 HP TDI engine and I'd like to get a little more power out of it with a chip tuning upgrade. The car is from 1996 and has 63,000 km on the odometer. Now, a friend told me that the engines in the Sharan have reduced torque output because the Ford transmissions supposedly can't handle higher torque levels.
Has anyone had any positive (performance improvement) or negative experiences with it?
[email protected]