How much information do you tell your insurance company

[PaulSmith]

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This is a joke ,some insurance company's  seem fine and others  don't have a clue.

And therein lies the problem. As Ricky says, many brokers and underwriters just don't understand what you are telling them. I would never detail mods on a price comparison site, because once it goes online, it stays online. Instead I would use the site to get a short list of brokers and ring them to 'confirm' the quote and nail down the details.