A story of two 2500hd's
 

Long story short, I hope.
A friend of mine has an 05 GMC sierra 2500HD, 6.0L with manual 5speed tranny.
I have an 06 Chevy silverado 2500hd, also with a 6.0L and manual 5 speed tranny.
Both of them are equipped with the same exact exhaust set up, same CAI's, Same little mods here and there (TB coolant bypass, plugs and wires). The only thing the separates us is he has installed a center force dual friction clutch and flywheel, not aluminum flywheel either so its like at the most 3 lbs lighter I think. He has 33 nitto mud grapplers and I have 285 nitto terra graplers, so I would assume these are lighter than the mud grapplers.
Also we have the same Blackbear in person tune, we were at the same meet.
Being stupid here and there, we'll spot each other in town and for the hell of it, run each other light to light, but always from a 2nd or 3rd gear roll. FOR THE LIFE OF ME, I cannot beat him, he runs from me every single time like i'm completely stock. It's not driver error either. No internals, no headers and no other misc crap added to his truck. At the very least we should be dead even. Even with my supposedly lighter tire set up I just cant pull from him like he pulls away from me, I actually get sick to my stomach when we do it.
Does anyone have anything reason at all as to why he is faster? Could it very well be his clutch set up? Did my tune go wrong? What gives? Are there any other mods he could have done that I just cannot see with the naked eye and I'm not talking about internal work. Just one time i'd like to stay right there with him just so I don't have to hear his mouth, without dropping coin on other parts of course.

you might have 3.73 rear end and he could have 4.10 rear end.

If i'm not mistaken, I believe all 6.0 hd's had 4:10's. auto or manual. I believe the build sheet stated 4:10's as well. I'd be f'n jacked if that was the case tho.

Driver error?

tunes probably aren't identical. he might be leaner and of have more timing.

look in your glove box and find out.

gt4 373
gt5 410

100% positive on 4:10's
I can promise you its not driver error. Even if I didn't know how to drive, going from a 2nd or 3rd gear roll is pretty easy.
Justin did the tune on mine first and then his right after mine. If we have both the same mods, theoretically, then why would he make his leaner and throw more timing at it? Come to think of it now, he told justin while he was tuning it that he planned to run a 100 shot. So, justin made some corrections to his to account for that. I think around 3 grand he pulled some timing from him so he could safely throw 100 shot to it after 3k. What I got from that was he was de-tuned slightly less than I was but when he hit the button for the juice everything would come into play. My tune is definitely there, but it just doesn't seem that its 100% on point. I had a yfz450 that I did a few mods to and I could tell when I was jetting it that it was close but had to be fine tuned. After playing around with it, I got it perfect, which was way leaner than I had expected.
I was under the impression that justin's tunes are pre-configured (89 oct or 91 oct) when he loads them and then fine tunes them accordingly. I'd like for him to take a second look next time he comes back to PA. This might be my problem. There's another thread on here regarding plugs. The OP stated he went from a .35 gap ngk ? to a .065 gapped iridium ac delco and it made a world of difference. I never knew that plug gap would make THAT much of a difference.

There's a guy around my town with a Chevy 2500 hd, and I have a GMC 2500hd. Both are autos. He has a cold air, Magnaflow, and self tuner. I talked to him at a gas station the day, I bought mine. But he pulled up next to me a week ago at a redlight. And the road narrows about 1/3 mile. We took off, I pulled away from him. We pulled into the gas staion he asked what mods I have now. I said stock. Come to find out he has 3.73's and I have 4.10's. He didn't what gears he had until we looked at his glovebox.

He slipped Justin an extra 50 bucks to make sure that his tune was hotter than yours :D

stop playing with my emotions bud lol.