Should be interesting, and until the car actually hits the street it's anyones guess.
The 6.1 SRT8 auto stock will take most LS3 Camaros unless they had very good drivers, we won't even bring the L99 into the conversation.
Depending on options; sunroof etc. the SRT8's weight wise are either dead even with or 200lbs. more than the LS3 2SS. NOTE: I'm talking dead stock cars here.
If you're talking 1/4 mile times I can relate my experiences:
Stock the best my SRT8 6 speed could do in the 1/4 was 12.87, and that was @ 20 psi. in the tires fighting wheel hop. I've been racing a long time so my car was set up well and I consistently will pull a sub .54 reaction time.
Before my bud shipped out on his 3rd tour he would run consistent high 12.60's with his SRT8 auto.
By comparison my 2SS L99 stock made a best run of 13.03.
I know a couple of fast guys with LS3's and they mostly ran high 12's low 13's when they were stock. I think the best I've seen was a 12.71 out of a stock LS3 and he's a damned good driver.
All of the runs were at LMP in Sealy Texas mostly made in the late evening in spring or fall so the air was fair but not great.
Now these are all times made with what I consider to be better than
average drivers. In the real world most SRT8's and LS3 are seeing in the mid 13's, with the L99 a tick slower.
On the steet in a stoplight to stoplight match there's too many factors to take into account;
How full is your gas tank?
How many people are in the car?
Is the AC on? Etc.
Some of the very fast street racers I know don't go to the track because they don't want
anyone to know their times.
That and I seriously doubt most of them are any where NEAR stock.
At the end of the day, these cars are more than just about 1/4 mile or 0-60 times, as most of you guys will never take them to a track, let alone seriously street race them. That's when you get into very subjective things like styling, features etc.
I own both cars and I can say this much:
I get more comments on the Challengers appearance from random strangers than the Camaro.
The interior of the Challenger is nicer, although the Camaro has some nice things like auto up windows and an easily moved flip forward drivers seat that the Challenger doesn't.
The Challenger has Nav and a hard drive radio that the Camaro doesn't.
My SRT8
with sunroof has as much head room as my 2SS
without.

The Challenger has an actual real back seat that adults can fit in and a much better trunk.
I'll take the 200 lb. weight penalty for those things.
I think the build quality may slightly go to the Camaro, especially paint finish. Actual mpg when both were stock also went to the Camaro.
If you're modding the cars the GM FI is much easier to deal with / dial in than the Chrysler speed density system.
Thankfully I'm fortunate enough to own both cars so it's a moot point.
If you're concerned about next years car being faster from xyz brand, than modify yours. Lord knows I don't leave anything of mine alone.