Technically you need a permit. I called my insurance company a long time ago on a similar issue and they said it would not be an issue in any settlement because insurance covers doing things not exactly by the book as long as there is no intent to deliberately cause damage. YMMV.
The change is perfectly safe, if done by someone who knows what they are doing… even to the point of making the insurance question moot. I think comes down to how you feel about circumventing authority and the associated fees.
