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Discussion Starter #1
I have a stock 03 Sierra 5.3 ECSB. what would be a good power upgrade that would give me more top end power. After second gear there aint nothin there. by the 1/8 mile im up to 72.11 mph at the 1/4 i go up a whole 15.28 mph to finish with an 87.39. also how can i find out what gearing my rearend is? thanks
 

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a.k.a. turbodan
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3,220 Posts
3.73 is a good all around gear. it gets the best performance without sacrificing too much gas mileage. i have 3.42 gears and i wish they were a tad bit taller like 3.73. as long as you have a posi(i think you do) you have a good setup in the rearend.

2 things i would like to know,
how tall are your tires and
what is your 60' time
Dan
 

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drive it like u stole it
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I have a 04 single cab, with the 5.3 and 3.73's and stocks tires and wheels. My 60 ft time is 2.27 secs.
 

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Discussion Starter #6
Hey dan thanks for the info.

at the time i raced i had on the stock tires (235/75/16, so about 29.88 inches tall) and my 60ft time was 2.28 secs.

now i have a question for you how can i tell for sure if i have posi, is there a code for that?
 

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a.k.a. turbodan
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I think for the 2003 they still use that option for your truck. it will be in the glove box as well . G80. I have 27" tall tires and i dont have a posi, with my 3.42 gears the best 60' time i can get EVER in my truck was a 2.42. thats horrible, so im imagining you have a posi. I fininsh at 90.55mph too, so i know my truck has a damn 14 sec run in her.
Hope this helps some,
Dan
 

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I put down a 2.30 60ft with wheel spin.I have not yet figured out how to get good traction without traction bars.
 

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a.k.a. turbodan
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charlie, what size and kind of tires do you have? have you tried to lower the air pressure at all? with a 3.90 posi, you should be pulling a 2.1 or 2.2. what are your times? I would like some more info and i will try to help as much as possible.
Dan
 

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Discussion Starter #10
im thinkin nitrous would be a little too much. what would be the next step down? also what are some good intakes out there?
 

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a.k.a. turbodan
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well, other than nitrous, i would say to just start putting all the bolt ons you can. headers, intake, exhaust, underdrive pullies, and a shift kit would help alot too...OR just get a nelson tune. i went from a 15.44 to a 15.04 and i have a 3.42 gears and a open diff, no posi!! i got in a group perchace so it was only 300 for me. its the best money i ever spent for 4 tenths off my time. give allen a call.
 
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