I switched from a factory headed 273 to a W2 headed 318. The 273 was 11.04:1 and had a CompCam292 hydrolic with solid lifters. It ran a best of 12.36 @109 in the 1/4. The 318 has 9.8:1 and a MP .541" lift circle track cam and just ran a 11.26 @119 a few weeks ago. The 318 has quite a bit more horsepower still to be found, but that will have to be looked for later as the 273 is being put back in very soon."