Rear end gear change with 20's ?????

[BP68]

Hello all,

I have a 2006 C1500 2wd ext cab 5.3 auto with a 3.23 locking rear end.

I added 275/55R20 wheels/tires. Doesn't a taller tire effectively raise the rear end gear to a "higher" ratio.

I know the wheels are heavy, and I want to improve acceleration and seat-of-the pants feel.

My buddy has the same setup and his dad has a 05 ext cab 5.3 with 3.73 and stock wheels/tires.

He says his dad's truck is stronger and feels like it would smoke our trucks.

Also, a guy at work has a 02 GMC ext cab 4.8 auto with 20's and 3.42 gear.
He got in the left lane and punched it from around 45 mph with me about a truck length ahead. I floored mine a moment later. He caught up to me and slowly started to pass me until the car in front made him slow down.

He does have a magnaflow cat back exhaust. Mine is stock for now. He has about 50,000 miles where I have less than 3,000

Did his 3.42 give him the advantage over my 3.23?
Does the stock exhaust hold these trucks back that much?
Or do I just need to get more "broke in"

I am not out to smoke everybody on the road, but I would have thought my 5.3 would at least run even with a 4.8



Thanks