Engine BHP

It looks many car engines have been de-rated in Horse Power (BHP), may be for emission std's.
How do they do it ?, is that we can reset the engine back to original BHP ,by turning a screw backwards.? or is it permanent change like changing the stroke length by modifying the connecting rod.
Experts appreciate your time..

It used to be as simple as that, back when I was a boy, jj. Now, of course, it's a little different. You need chip specialists to do the screwing around for you. Unless you have an ePROM reprogrammer & some spare knowledge lying around.

Contact Viper. He should be able to do something for you.