I phoned Admiral about two months ago to ask how much decats, y-pipe with racing cat and uprev would cost, the quotes me £50 for the exhaust insurance but wouldn't even touch the the uprev... so not that good for mods for me, although I have 0 years NCB as I haven't owned my own car in a while.
I had an accident somewhere around 1999 while insured with Admiral and the car was a write off (note to self: never try and avoid foxes!), after being offered an initial fairly low value for the car (as expected) I compared my car to the current value of cars on autotrader and they were happy to pay the like for like price.