Has anyone extracted decent power improvements from programming on a bone stock car? Or is the stock ECM pretty good?

Reason I'm asking is just because I want to know.

If gains aren't gonna happen, when does custom burning come into effect, after headers, cam, gears, intake...when?

Thanks

ah to date the best ive seen with a factory freak is like 15hp and 14ftlbs of tq. although ive seen some 4-5mpg improvements and better off the line response as well.

custom tunning comes into effect any time youve altered the airflow chareteristics of the engine

throttle body,headers,cam,head,intake,porting,compression,fuel injector ( to compenstae for size only if no other mods have been made ) thats the jist of it.

tuning came to my life when car simply would not run due to mods done. Or it barely ran but i had concerns was LEAN.