You can download maps that are for engines configured the same as yours i.e. same mods, then upload them to your ECU, but this is with a K-Pro, on the K20 engines. Other K20 ECUs e.g. K100s cannot be altered via a laptop.
mapping aint too bad tried a bit myself. wiv a honda cbr!!if you can get a cheap rolling road then thats one step. you can get a basic map for the car with the ecu normally but then you can tweak it yourself/professional to work even better to your spec. you may aswell get manifold and breathing sorted first.
you could re map it but as with most hondas they are pretty well setup already. if you are putting on breathing mods and exh, getting a new cam and port polishing then maybe get it remapped. im sure you can't remap a standard ecu but if you buy a new one like this thread suggests thats ALOT of money. you can buy chips which you insert into teh loom and that changes the map slightly which can give you alot more response and power. they aren't cheap either