armchair theory on ecu reflashing

[yariphilia]

lol, as the title states this is purely skeptical... upon discovery of j2534 tools i was wondeering if it was possible to use these to reflash our ecu's and reprogram them with performance in mind. j2534 tools were created with the intention of "universalizing" pc to car ecm communication. tis, which is toyota's technical information service (iirc), would allow your pc to communicate with toyota ecu's. tis is an online database that also includes factory ecu programming. afaik this is common practice used everyday kinda stuff. the skeptical part is... could this process and tools be used to reflash our ecu's with performance fuel maps? much the same way openecu is used to flash subarus and evos. instead of reloading factory settings, could one load their own? as far as ive been able to find out a basic j2534 passthru tool costs around 300 or so and a 2 day subscription to tis is 55. and lastly, one would need to know what they were doing if they got that far lol. honestly i know a days worth of browsing on the subject and am very curious. if anyone (ctscott) has any info on this, im waiting anxiously.