X 3 for DD... I can testify from 30 years experience, and now up in a full blown modified.
Before you go buy/build a killer engine... go buy two eggs... put one under the gas pedal, and one under the brake pedal... easy on... easy off...!
I have seen many very smooth drivers with small engine cars beat the pants off the big buck spenders with insane powerplants.
If you are running IMCA, USRA or any other specific rulebook you better memorize those rules inside out... as a bad azz car with a killer motor is of little consequence when you are black flagged and DQd...!