both gp2edit and gp3edit have an option in performance -> car settings section called "car power fixed" or "selected team dependant" . or similar that.
Basically, by default is setted on fixed, and that means you as player in car have got the same horse power, also with more powered or less powred team.
If you change this option in your carset and export to game that, you will have horse power team dependant in base of the carset values.
But there is an other question.
The carsetup you can use as player, also if set separated carsetup for each round player, will be the same on driving by cpu. That means AI will try to drive
with the carsetup used by the player and it should be more faster or less faster than you (it depends by setup ) .
So, in any case, the pc will not remain on the same performance level showed by the player.