Actually it's was designed to help on top end, as in creating a ram effect. The first time i ever saw one was at Rockingham in 1968, the first race they ever had, in fact the asphalt was still wet when we got there. There was a guy there that had a 427 ford super stocker, he was a tenth quicker than all the hot dogs, and i mean ford sponsered cars. The factory immediately protested the guy, but the protest didn't stand up since there were no rules covering that situation. That was on Sat. by sunday ever prostocker there was running one including Sox and Martin. It was funny to see a nobody showing up the factory teams. Incidently i was running B/Mod production class with a 67 Camero conv, we won the class, but got beat by a Sox and Martin car in the 3 rd round of elimination. We did run 10.93@ 126mph @ 3520lbs, not too bad a 100 yrs ago with mufflers. O'h how i loved those days, damn i was only 30 yrs. old then.
Zip.