On my LC I paid £840 Fully Comp with 1yr NCB on my 24th Birthday. Asda (who I was with when I had the 1.4Clio RT) quoted me £1350!!! Sod that!
Admiral was the best but only on the pay up front deal, not the monthly. Im with Direct Line now... as I found, Direct Line under writes Tesco, so are the same but cheaper than Tesco.
I think I'm right in saying that unless your insurace company are going to pull out the ECU and check, then they arnt going to know whether you had it remapped or not. From experience, I dont think they would go into that much detail. It's the visible mods which they'll prob pick up on. I think Im right?!