This is quite different from the bloke who puts on some chrome exhaust tips, then gets called out on the Internet though.Both my MGs are extensively, and invisibly modified. Nevertheless I have advised the insurers of all the details - probably 4 or 5 pages of A4 listing everything.
The insurers don't seem particularly concerned as I have over 50 years NCB, and the mods I have made don’t only provide more power, but also better handling & braking.
And quite correctly, brakes, suspension and then performance.
Most times, you don't even need the performance mods.
That's how it goes in Club Bike Racing.