Unlike most on here, ive fitted a few of these for people after they've fucked their ecu trying to do it at home, road tested and back to back with standard too on multiple cars.
Top and bottom is they're alright ish and don't deserve to be put in with resistor style chips etc. Ive collected quite a few maps for various states of tune now.
I saw 5bhp and 5lbf in a back to back rolling road test with another map I had found somewhere.
Last dealing I had with that ebay seller was somebody sent me an ecu and a chip from them to fit, turns out the chip was blank but he soon got a new one sorted out.
The biggest issue ive seen is that no two engines are the same and now as they get older they only drift further apart, sometimes a generic chip will make one engine go like stink and the other cough and splutter. Ive also seen some quite frankly dangerous maps that somebodies spent no longer than 5mins creating (think just adding x amount of advance and injector duty across the entire map then clicking save).
If anybody is local to me im always happy to stick one on their car for them to give it a test drive see what they think.