They suprised me too a few weeks ago. Insurance was up on my vw transporter, its a hig van but I only use it for commuting, moving own goods and camping.
Most insurers wont touch it or will only offer a commercial policy, so I had a quick look on the vwt4 forum and aviva seemed to be mentioned a lot.
Rang them up, all mods declared, £100 cheaper than anyone else without mods!
Then the bloke asked if I had any other products with aviva, which my company pension scheme is, so he knocked another %10 off