[Shane@DBPerformance]

You probably wouldn't max out the stock 450s at 21psi on a 14B. The main reason people have to get 550s on DSMs is usually to avoid fuel cut by going overly large on the injectors and fooling the ECU into thinking there is less airflow.

Are you trying to run 21psi with a stock SMIC though? Pump or race gas? The 14B is going to be a heat generatoring knock machine at 21psi, unless you are on E85 or race gas.