Mine is a 1989 305, a california car. I changed the ECM box years ago and put on a non CA on.

I remember around the time there was a seller on ebay with good feedback from user that was selling a programmed custom tune already loaded on the ECM box and all you needed to do was swap the box.

1- You know which seller it was?

2- Do I get any noticeable increase if I swap the ECM?

Thanks!

 

You don't state what ecm your trying to upgrade.
8746 , 165 ?
The tunes should be 50 state legal and I wouldn't expect a hp increase between stock tunes.you might have a different tune if it's a rare export leaded car.