Well it looks like the quality OEM .681 5th gears are no longer available. Not to say we didn't try.
Here's the next best thing
The .700 gear will drop RPMs by about 8 percent.
If your car has over 100,000 miles it's recommended that you change your GEAR OIL (2 liters necessary) as well as your TRANSMISSION SEAL with the 5th gear. A 5th gear mod will significantly drop the dB level in the car, making travel a much more pleasant experience for all involved. This works with all manual transmission VWs from 1996 to the present, as well as many older models. Set includes large gear, small gear as well as the concave washer. The retaining bolts are offered here (lubed with motor oil and torqued to 60ftlbs + 90) and are recommended to replace.
Pulling the gears is VERY easy! Don't sweat the puller instead you are supposed to heat the gear using an electric heat gun to 100C, the gear(s) slide right off!
If you try to pull the gear without heating it you will crack it nearly every time.
Same thing goes for reinstalling, heat it to 100C and it slide right onto the shaft.
Kit consists of
1 x Large Gear - 02A311158AF
1 x Small Gear - 02A311158AM
1 x smaller concave 02J washer