It's there to stop the speed sensor unit overheating as it's 10'' away from the exhaust, I presume.
Doesn't look like the Mk4 section gets used much these days, SAD. A friend still has my old 1.8T hand-me down - 240k miles, every-thing original except P/S pump, Starter motor, Alternator and Clutch....... ( Rads - Complete Exhaust - Turbo - Gearbox - A/C - ALL ORIGINAL and Engine never been apart!!! ) It gets pasted as well - £800 on 205 Michelin Pilot Sport 4's every year !!
Not bad EH ? Do you know better ?
Cheers.