I've bought a Mk4 XR3I that is currently off the road as i'm zetecing it and fitting a few new goodies... Whilst it's off i want to give it a full underseal and do the arches, Just in black.

What kind of prep work would i need to do? I've been advised against not using waxyoil as it's not very protective and been told Shults (sp) is what i need. Any advice or links?

Thanks