This long awaited video covers the removal of certain factory systems on Mk4 1.8T Golfs, Jettas, and GTIs, as well as could assist in similar applications on Beetles and Audi TT’s. In Part 1, the secondary air injection system, the N249 which controls operation of the diverter valve, and the Evaporative emissions system are all properly removed from the engine bay.
There are multiple reasons for doing this, with the major one being that there is less clutter in the engine bay making it easier to work on in the future. Aside from this, it is common for the N249 and/or N112 solenoids to go bad causing vacuum leaks and poor operation of the engine. By removing these systems (which rely on boost/vac readings), the remaining necessary systems of your engine should be more reliable.
Keep in mind that doing this modification may be frowned upon by your local authorities and emissions check stations. Do it at your own risk.