First off hello! 1st post but I prowl these forums regularly - I tune my WRX with ECU flash all the time but my buddy has an 2004 EVO VIII that we want to start working on. It has been tuned pretty poorly from what I can tell, and his previous tuner pretty much just ignores his calls now.

His car is using rom 96420011 which isn't really used at all from all the reading I have done, everyone pretty much replaces it with one of many other better ROMs.

He wants to go back to the stock map (a good idea IMO) my questions-
can he use the 96530006 rom (aka the 'universal' rom)?
His tuner used a JDM map sensor to tune the car and then swapped the original back in - do I need to do the same thing or do I assume correctly that if going back to stock that step is not necessary?

I have read for hours on end through these and other forums, I have read almost every page in the ECU wiki and have not found answers to these Q's there so if I missed something I do apologize. Any help is appreciated.