Are they going to be checking the actual HP of the car. If so you should probably do something that will reduce high rpm power and fatten up midrage TQ. Cam is a good one as said above. With the right cam you could reduce peak HP #s but really fatten up midrange Tq. TB spacer/restrictor is another if you can find the right combo. If all else fails maybe reduce your rpm/rev limiter to exact HP # and shift early. That way you will not reduce TQ or area under the peak at all.