Yes, it is still best to clay, as this removes surface defects that polishing won't touch. To test whether you need it, put your hand inside a sandwich bag, and push over the paintwork. If you feel anything other than a perfectly smooth finish, like wet glass, then you need to clay. You'll see the defects the clay removes, as it will change colour.

If you're interested, i can supply you the products, and give you detailed support and instructions along the way, as the instuctions on the bottles are only basic. Give me a shout if you need anything

Gareth