The Demon driver didn't have much to mess up on with the auto and slicks. Actually, I know a really good Mopar guy I knew had a friend that bought a '70 Duster 340 4 speed 3.91's. With the only addition of slicks tried to get into 13's and couldn't. Without changing parts, they did bump ignition timing and tried everything on the launch. Went 14.0's to 14.10. I think the numbers are pretty much on Que. Most magazines that tested these cars had them around 14.4's. I can tell ya, you just didn't grab a 340 car off the lot Friday afternoon and turn 13's Friday night. But neither here nor there, it won't have a bearing on what the 5.2 runs. :)
