[stamford]

You are obliged to inform your insurers of such modifications. In the event of an accident and an assessor being assigned to evaluate the claim and if they find non-standard parts fitted they will void your insurance. This will then be referred to the Police as an offence and you will pay dearly. It really isn't worth taking the risk, not only is it wrong you should also think of what could happen if the car was involved in a serious accident.

Anything that moves away from OEM is obvious and not exactly hidden. ITG is obvious, as is manifolds and sports cat. Replacement exhaust is on the fence as a stainless replacement can be regarded as quality replacement rather than performance, but if you already had the former parts fitted then it'll be seen as modified.

Steering wheel, tough one that but as long as the airbag still functions correctly, but no knowing that unless it gets deployed!

I know it is tempting to 'forget' to declare but it isn't wise to do so. I have always declared mine. Remaps would be hard to determine unless they interrogate the ecu. Would the fallout be worth it?