Not just you - what if you injure or something worse someone else in an accident. The insurance company will investigate and rightly so deny the claim, you become personally liable.
It's irresponsible and not a gamble anyone should take. Can't afford to declare on the insurance, don't do it. Only something a very foolish or selfish individual would do.
Just my $/£ 0.01 worth.
J.
^ 100% this.
What if a car with a tuning box fitted that hasn’t been declared to the insurer is involved in a front end impact that means the tuning box can’t be accessed to remove it before the car is trailered away for the insurer to assess whether or not the car is a write off? The driver might also have sustained injuries so they’re physically unable to remove the tuning box, so the insurer would find it.
Anyone considering not declaring vehicle modifications should consider the potential consequences. Not declaring modifications to an insurer constitutes insurance fraud, which is a criminal offence. Anyone found guilty of insurance fraud ends up with a criminal record, and have their details added to an insurance fraud database, which is available to view by all insurers who subscribe to the database.
Also, anyone convicted of insurance fraud needs to declare this conviction when applying for insurance in future, and an insurer who is prepared to offer to cover (some might not) would almost certainly apply a sizeable premium loading.
Insurers customer checking processes have become very sophisticated in recent years. Most will probably have a checking process against various external information sources such as the fraud database, so anyone convicted of fraud but fails to declare it when applying for insurance cover is likely to get found out anyway.
IMO honesty is the best policy. Failing to declare modifications to an insurer is not worth taking the risk, and always check with the insurer before making any modifications to ensure a) they’ll cover the modifications b) you can afford any premium increase they might charge.