The 996 was introduced in 1999 but I expect there would have been a few 916 models hanging around in dealers that could have been registered as 1999 or even 2000 plate bikes.
1998. During that year the final 916 series bikes and the first approx. 1900 of the MY99 996s were built. As Antonye has stated the registration year does not always tie up with the model year and it is common for a bike to be built the year before its MY. In some instances I have seen bikes have been built up to 3 years before their first registration. The number plate is not the best indicator of the build year
