Power and increase are not something to tell an insurance company!
"I always thought that stainless steel were fitted as standard

Have a hard time finding any round here without one.... Just replaced the old one with an aftermarked cheaper option, your honour."
I have heard mention of CCI (Competition Car Insurance) on SELCOCK gets good press (Free trackdays too!) could try Adrian Flux but don't ever try and claim by all accounts. Monkeyed me about over addresses but quoted cheap.
HTH
Rich