Thanks everyone who advised me on changes! Here is a pass I made yesterday against my brother in his SRT8 Charger...

first time spraying so don't give me a hard time about my reaction time and lack of burnout

http://www.youtube.com/watch?v=siuLbUGiXXo

Now looking for the next step... can I crack into the 11's with this car?

Current:
4996lb C-Body
446CI, Eddy OOTB heads, Performer RPM Intake, Quickfuel 750 holly, Wilson manifolds plate system (spraying 150 out of the hole), HP Manifolds into 2 1/4" exhaust and dynomax super turbos
Stockish trans, 11" converter stalling around 2800 I'm guessing

3.91 Suregrip w/ 275/60-15 Mickey Thompson ET Drag Radials...

where should I go from here???!

Car is HEAVY and everyone was impressed at the track.....now I'm addicted to get the barge into the 11's....there are tons of lighter cars running 9's and 10's, and my '68 Charger will be a 10 second car when done, but there's something cool about seeing this huge barge beating Mustangs and Camaros at the track...

Long tube headers,2.5 mandrel bent exhaust,and a converter built for your setup.
Did you post cam specs??

Put the motor your building for the Charger in it and quit screwing around

heavy car might want lower gears 4.30
what did you cross the stripe at?

Your MPH is about right for that time...and shows you HP will have to go up to improve. I think you've maxed out your combo to be honest. Thats really good for such a big car! I think to go faster will take some engine work and/or more juice.

Cool stuff.
I agree with the larger 2.5" exhaust-diameter AND full length 1-7/8" prim. headers. Perhaps even install an X-pipe crossover.
You want all the torque you can get to that weight moving. You might also want to try smaller diameter tires to artificially improve the gearing to see if that has any effect.

Work on your reaction and start saving for a Dana

I would consider staying with 1 3/4 headers.When I switched from 1 3/4 to 1 7/8 I had to retune to get back what I lost.Conventional wisdom doesent apply in a heavy vehicle.
Maximum low end grunt is what's needed.Moving the powerband up doesent help that much unless you have deep gears and a stall to keep it in the torque band.Then it loses some of it's fun to drive factor.
I have had a backbraced 8 3/4 in mine for 6 years and it's still ok.I worry about twisting an axle more than anything.