I've had Progressive insurance for years (due to price, not their politics). They insured my 2009 Bullitt which I totaled after boosting the power to 643rwhp and then running out of talent. Had over $40K in modifications including swapped T56 trans, forged motor and supercharger pushing 15 lbs of boost. BMR K member and front A arms, full BMR rear suspension, etc. In all the years I've had them, never once has anybody asked me if I had a modified suspension.
Heck, I have air shocks on the back of my 2002 F150. Does that count as modified suspension?
Of course I never tried to add to the insured value. When I totaled my Bullitt they paid me full retail blue book value. Of course I bought it back and parted it out.