Hey Steve,
A-Plan in Bletchley for me, and they're pretty relaxed about any mods, like those Adamesh pipes you have. Premium is rising, this is 2nd renewal, and it's crept up from under £300, to close to £400. This is with 4 named drivers, fully comp and only £200 excess, underwritten by Markerstudy I believe.
Hope this helps, Russ