Since i'm too lazy to care about the numbers. Most auto cars run a bit slower than their manual counterparts. given it's a stock auto t/a that's where i got my assumption. didn't the auto ls1 cars come with a different gearing? maybe i'm just making shit up now lol.
Either way, OP... you should probably become quite a bit smarter before you start doing dumb shit.
You are correct about the gearing being different. Automatic Fbodys had either 2.73 or 3.23 gears while 6speed cars had 3.42's. But even an auto Fbody would walk away from a stock Cobra. SN95's come with 3.27's stock(if there are any left with stock gears) which leave alot to be desired from the high revving DOHC. LS1's can range from 290-315+ rwhp stock depending on transmission and year of the car. The most I see from Cobras is in the 260 range at the wheels when stock. Not downing Cobras here, but they are just down on power and the weight difference isnt great enough to overcome it. All a SN95 needs though is a set of 4.10's or 4.30 gears and maybe a couple of other bolt ons and the game changes. As I said the stock gears suck balls, but then all the LS1 has to do is change gears and your back to square one. Automatic LS1 cars improve greatly from a set of 3.73's. I plan on installing them in my car when I get a new rear end.