I just read through the whole thread here and didn't really know where to post this in reply, but in my experience, if you start modifying things, it really pays to shop around some of the less well-known, specialised insurance companies. Most of the main 'high-street' insurers make so much money they don't need the business from people who modify their cars. This is probably gonna annoy the hell out, but a couple of years ago I converted my car to fuel injection. According to book figures, I should've had around 20bhp extra as standard (it felt like it too!) - I also fitted an induction kit but this was due to the fact I could no longer use my old air box & filter rather than for any performance gains. Now, I made no modifications whatsoever to my brakes, suspension, tyres etc. I was with AXA - they flat out refused to continue insuring me as did most of the other insurance companies I'd heard of. I ended up calling Adrian Flux, who got me a premium which was £20 lower than insurance with AXA the previous year.
IMO, all insurance premiums are based on statistical evidence. However, how those statistics are used is at the mercy of the insurance companies and, of course, what they eventually charge you doesn't necessarily have to reflect
*every* piece of evidence at their disposal.At the end of the day, insurance is probably one of the only times in business where it's actually OK to discriminate against people based on every single aspect of their lives.
Chris.