Big difference between the 8 spd autos and the 6 spd manual - a lot easier with the 8 spd auto to do it but it can be done. For one thing - there's more gears which keeps the engine in a more favorable RPM range for a longer period, and secondly, a human can't shift as fast as a computer.
I haven't done any tracking since I moved to Michigan 6 1/2 years ago, but my typical runs used to be 12.8 to 12.9 - I did a couple 12.7s - once at Cayuga in early Oct - upper 60s temps, and once at Empire Dragway - my former home track - in Western NY- which was NOT sea level - it's about 1100 ft elevation as I recall. My best was at ATCO in NJ - 12.6 at 110 that was my first run of the day and I launched conservative too - unfortunately it was a very busy day, lots of breakdowns and dudes with imports oiling the track, and I didn't get another daytime run while the track was sticky from sunshine - I know I had a 12.5 on tap that day.
You need drag radials with a manual - primarily because it eliminates wheel hop at the higher launch RPMs you need to hit 12s. I would typically launch at about 3500-3800 RPM. On 20 inch street tires you'd probably be hopping badly. And you don't side step the clutch or anything like that - there's some 'feel' to hitting it right - ideally - you want to increase launch RPM until you
just start to spin ever so slightly on take off. You'll make 3 shifts in a quarter - 1-2, 2-3, and 3-4. You'll get better times if you don't lift the throttle between shifts. And mind your shifting technique from 2nd to 3rd - don't grab the knob - push forward with the heel of your hand
As far as mods I have - AiRAID CAI, 180 degree JET t-stat, JBA shorty headers, Solo hi-flow cats, and a Heartthrob cat back exhaust - pretty minor stuff. I have a Trinity tuner, and I did pay a fella named Brian at Drag On performance for a custom e-mail tune 11 years ago -he eliminated something that Dodge includes with the manual transmission cars - Buck/Bobble - which is a timing pull when you shift. You don't want that - I suppose it protects the drivetrain a bit (Dodge concerned with warranty repairs, reasonably so) but it hurts ETs.
I have a few other 'tips' too - turn the heat on full, try to keep your idling while waiting to run to a minimum- Ideally my t-stat is just opening when I'm at the tree - - run with 1/4 tank of gas (no more than 3/8s), leave your spare in the pit, and the trunk liner to save 45-50 lbs.
Good luck!