has anyone jabba'd (or similar) their company car? did you have to inform the hire company etc? just curious

Yes you would have to inform them and no, they're not very likely to allow you to do it - they own the car, after all ...

Yes, mine is being chipped tomorrow. But the garage I lease from are carrying out the work.

I would imagine the lease company in your case would not be to happy but you could always make the call anyway. Worth a try?

On a related subject, there do not appear to be any restrictions on modifying a car you are buying using Skoda finance. But if you take out GAP Insurance at the same time, cover is not provided where the vehicle has been modified other than in accordance with the manufacturer's specifications. :(