Heres a video of a local guy with a regular cab short bed silverado; cam bolt ons and some Nitrous running 11.5x. It still had stock heads, stock bottom end, stock intake.
http://rgvtruck.vidiac.com/video/6862f80c-b314-4aaf-89da-9afa00a0107b.htm
http://rgvtruck.vidiac.com/video/6862f80c-b314-4aaf-89da-9afa00a0107b.htm