What's the flash count in VCDS? It should be at 1 if it's just been Revoed. If it's greater than 1, it's been overwritten elsewhere. The Flash count is basically a counter for EPROM overwrites and was an easy way for dealers to check if the ECU was factory or not, before the days of the more sophisticated 'TD1' warranty void flag. Factory flash count being 0 obviously
Anyway, if the flash count is 1, then it's likely still Revoed, but an easy way to confirm is to pull the battery. If the car is slow afterwards, it's definitely Revo software.....but you'll need an SPS switch to get your performance back.
I went through this with mine as well. No history from the previous owner, but flash count was 1. Took it up to my tuner (who is/was also a Revo dealer) and he couldn't tell what the software was either! In the end we managed to over write it with his own tune as he has the necessary Revo hardware to facilitate it. Without it, you can never change from Revo, short of buying a new ECU, or maybe visiting Revo HQ and have them take a look at it.
