[stephen low]

Strictly any modifications away from standard should be engineered.

Realistically though, changes such as forced induction, ie big HP increase, are when you should revisit the engineer.

That said how many have made such changes and seen the engineer too, not many I'm guessing.

This then poses some insurance risk amongst other issues eg EPAV fine of about $10,000 for modifying a car's emission system.

How does say supercharging play with emissions, do they really alter?

Cheers