Its a new map, but with the intimate knowlege Karl now has of your engine and what he will have gleened about its VE form how it responded to boost from the T3 etc (whihc will give him a feel for what cams and head mods it has) and with his experience with different turbos etc, i bet he can get it pretty close without even seeing the car!

So its not going to be as bad as starting from scratch, but its still going to mean changes to a large number of load sites, in fact almost all of them!