The surprise is not that the CNC-d Dart Pro 1 227 heads produced more horsepower than smaller as-cast 180 heads, but how well the as-cast head did. In terms of peak power, the CNC heads offered only an additional 10 hp and actually lost out by 3 lb-ft to the smaller heads in peak torque (476 vs. 479 lb-ft). This test was not about which head makes more absolute power; it was about which head was best suited to this application. Though a 500-plus hp stroker small-block certainly qualifies as a healthy street motor, the mere fact that the as-cast, Pro 1 head did so well demonstrated they were serious players. This test also demonstrated that the larger and more powerful CNC-ported 227 head would be better suited to a combination with wilder cam timing, increased displacement and/or higher compression. The airflow offered by the CNC heads indicates they will support well over 625 hp on the right application, so make sure to choose wisely when selecting head gear for your engine.