the map wont change, but it the mechical side that loosens up and improves performance, so whether you map it now or later you will still get the same out come. ie brand new car 180bhp, 20k later goes upto 190bhp, map it brand new say you gain 5bhp which is norm, so you will have 185bhp 20k later it will be 195bhp. if you leave it alone and get it mapped at 20k its still going to be 190bhp with 5bhp after the map. also the ecu is adaptive anyway, theres only so many things you do before the ecu trys adjusting so you cant get anymore.