First of all, the transmission issue (already commented on, but this is from the initial press release for the 1LE):
"While the Camaro SS features a Tremec TR6060-M10 for all-around performance, the Camaro 1LE features an exclusive Tremec TR6060-MM6. Paired with a numerically higher 3.91 final-drive ratio, the close-ratio gearing of the transmission is tuned for road-racing performance. As with the ZL1, the 1LE transmission features a standard air-to-liquid cooling system for track use."
Second, traction is HUGE in drag racing and the Goodyears on the 1LE stick like glue when they are warm... much better than the Pirelli's on the SS. 60 foot times mean everything for drag racers.
Third, subjectively just about everyone who has a 1LE and who has previously owned an SS reports a quicker "feel" to the acceleration, myself included. I hope to have numbers to back that up if it ever quits snowing here in MN. I attribute that to the combination of changes (the 1LE is more than an SS with a different suspension). Gear ratio, transmission, wheels, tires, exhaust, electric power steering.... how is it so hard to see that could make up at least 3 tenths?
Fourth, drag strip times are impacted by weather, so same car on a different day will produce different results... same car with a different driver will produce different results.