RACV aren't too concerned with mods as long as they're legal, the main concern is the actual financial interest in the vehicle.... You wouldn't be able to insure a vehicle that's worth $25,000 for $50,000...... It's a matter of what you want back. So if you plan on spending $25k on mods there is very little chance you're going to recover all of that if the cars written off. As for the repairer it's always been you're own choice as long as I can remember.