No problem I had a long day myself.
Going by my Moroso power speed calculator it's telling me that 6200 rpm at the stripe with a 28 inch tall tire and 4.10 rear gear puts you at 126 mph, ET in the 10.55 range. A 4.56 gear and 28 inch tall tire puts you at 6400 at the stripe and 118 mph and 11.2 et. I'm by no means an expert but going by what this calculator says you could use some more rear gear. I would skip the NOS for now and put your money into gears and chassis tuning because it sounds like you're closer to the 10's than you think.
Let's look at the math (this is for all of you who want to go quicker and run faster....if that is NOT you, move along) because we have real, known numbers. Most of them. What we don't know is measured HORSEPOWER and measured WEIGHT. But what is here is a good start.
We have a 28 inch tall tire, 4.10 gears and a mile per hour of 118. We can learn a bunch from this, if we ASSume a weight of 3000 pounds.
We know (again, assuming we have established the correct weight) that the engine, by the numbers is producing about 380 HP. If the car weighs the more likely 3300 pounds, it is making about 415. My best guess is it is closer to 3300.
The second thing we can learn from the numbers is at 118 MPH, with a 4.10 gear, the RPM at the finish line is 5800 RPM. It would seem the car could use a 4.88 gear if the MPH never changes. If you can make the engine produce enough HP to pull the 4.11 gears to 6400 RPM (just for the sake of discussion here) on that same tire, the car SHOULD run 10.30's at about 130 give or take a bit. That would mean the actual horsepower was about 550. If you don't have that much horsepower, you need more gear.
Third, we can look at the Starting Line Ratio, which is simply the multiplication of first gear by the rear axle ratio. I consider anything under a 10.5:1 SLR too tall, except in cases of exceptional horsepower or ridiculously long strokes.
Again, ASSuming a 2.66 low gear and a 4.10 rear axle we get 2.66*4.10 = 10.91. That is pretty tall for a 4 inch stroke and 3000 pound plus car. If the car has a 2.44 low, that poses even tougher circumstances. That would look like 2.44*4.10 = 10.004 and that would put a pretty good strain on the clutch.
What if you have a 2.66 low and a 4.88. That would be 12.9808 and would reduce the load on the clutch on low gear.
The other option is a 3.09 low gear box. It would be this when calculated out:
3.09*4.88 = 15.0792 and that would make the car move in 60 feet.
There is room in almost ANY combination out there to look at your own numbers and see what you have. Most guys need to spend more time on chassis/gearing than they do on power adders.
It's all fun with numbers.
