That's decent for an otherwise stock LT1. If you want to go faster, you will need some headers, maybe a camshaft change, certainly some PCM programming, some lower control arms, and a swap to a looser torque converter. That should do it for low 13's. Working on the launch with some drag radials should tickle the E/T into the high 12's.

All of the factory stock Z28's of the mid-90's were running high 13's. Those numbers were great and represented a full-second faster than the Z28's of the late 80's / early 90's. When the 1998 Camaro Z28 came out, the good LS1's were mid-13 second cars when factory stock. Some of them were high 13-second cars. Some of the six-speed cars were able to squeak a 13.2 second quarter mile out of the traps. I don't think there were ever any 12-second F-body that were factory stock with possible exception to some of the tuners from places like Mecham or SLP. Oh, and AL's Formula of course!

 

My 02 SOM 6Spd Z with 9,500 miles on it ran 13.2@108and a half
100% factory down to the ****ty tires and sediment filled paper filter
car is fully loaded t-tops..weighs 3,660

 

Best way to know what your car runs is to run it at the track. I have watched six speed ls1 cars run 15's at the track because the owner couldn't drive. I have watched others crack into the high 12's. It's easy to speculate on what your car should run. Spend $15 and go to a test n tune night at the local track. It will be the most fun you have had and it will be exhilarating and humbling at times.

 

my car went 13.2 with lid, loudmouth 1. Thats it. AUTO and 2.73s gears!!! with a 2.0 60ft and still have the ls1 intake.

if your ls1 car goes high 13s you have a problem or your DA blows.

 

I went 13.1 @ 108 on a 2.1 60ft bone stock. Nothing removed, and rsa's.

As far as stock 12s, been done and documented.

 

My 00z went 13.5 at 104.1 with a 2.1 60; on street tires (245s) with a catback and k&n filter 6 speed with a ~3000 launch

 

Buddy's '01 or '02 Z28 M6, stripped (wind-up windows!) except for T-tops (weird, huh?), totally bone stock, nothing removed, on OEM *all-season* tires did 13.4 @ 107.x at New England Dragway way way way back when.