If using silicone get some quality stuff as the cheap stuff just doesnt last, you also need to seal the little rubber dump valve on the air filter housing
Tis nice and easy job. I did mine a couple of weeks ago on a 300tdi defender. I would take your time to get the template lined up correctly. The instructions mention a 16mm hole for the 3 wing holes but 12mm works fine. I used normal bolts on the wing studs whilst I lined up the windscreen frame bolts then use the nylocs when fixing finally.