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Discussion Starter #1
hey all,
it seems a duramax is not in my future now, too expensive, so i'm going with an 03 and up gmc quad cab, with a 5.3 liter and i want to know what is the best performance mod for this motor, i've heard alot about hypertech but some say no power gains with 87 octane. how much power incrase are we talking with a hypertech, others i've looked at are quadzilla, superchips and a few others does anyone know about these, and there power gains and mpg gains? i'm also planning on getting 32x 11.50x16 tires, how much mpg loss can i count on with this and what does the truck get stock? i also plan on getting some kind of exhaust, perhaps headers and throttle body spacer can anyone tell me anything about these and if there are any other performance mods. and finally, can you stack mods on a gas like you can a diesel, like say a hypertech programmer and like a jet performance module or something. SORRY for the 20 questions but i wanna know all i can and dont want to waste another thread with more questions. thanks in advance

christman
 

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This is a 325 ci pushrod GM V8, the normal goody mods work the best. Head work, cams, intake, exhaust... With the diesel, you can use a programmer to add more fuel to create good power. Not quite the case with a naturally aspirated gasser motor. I'm quite impressed with the 5.3L and has pleanty of power to get into trouble and enough potential to make a pretty good runner out of it. I'm not sure you will find all the answers at this forum for what you are looking for. The 5.3L is based off the LS1 5.7L so you can check out LS1 forums to see what add ons are the best.
 

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If you've got the money, consider going with the 6.0L. I've driven an '04 CC/SB 2500HD 6.0L, and it definately had balls to it.
 

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Don't waste your money on a throttle body spacer, put it into the air intake, exhaust and custom programmer (Westers, PCM4less Wait4me, etc...)

DEWFPO
 

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From what I have seen, Headers don't really don't do much for these trucks, because the manifolds flow pretty well. For the cost, Headers don't give you enough of a gain. I put true duals on mine with an H pipe, and I opened up the airbox, by taking the piece that attaches the box to the fender. If you unsnap that out of the box, and it doubles the air inlet.
Some people don't like this, but I took the screen out of my Mass Airflow and let that flow easier. I have never thrown a code, or had any issues with that mod. Those intake mods don't cost anything and the thing really talks when you step on it.
I have to agree with dewfpo, the throttle body spacer, is probably not going to do much, for the cost.
The intake, the duals will help. A good tune which gets the torgue management out of the computer will help as much as anything. That should get you going. If you want more than that, I guess you go to a small super charger. That would give you more torque.
 

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For the 5.3 I think the best mod would be a set of 4.10 gears, then an 87 octane tune for better engine & trans performance.
JP
 

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Discussion Starter #7
what kind of mileage should i expect with 4.10 gears on that truck and how much would that cost? THANKS for all the replies guys, how do i get set up with a custom tune, what all would i have to do for all fo that. cost?? etc...
 

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christmanz;1606662; said:
what kind of mileage should i expect with 4.10 gears on that truck and how much would that cost? THANKS for all the replies guys, how do i get set up with a custom tune, what all would i have to do for all fo that. cost?? etc...
My brother did it to his 99 Z71 and he picked up 1.5 mpg around town, his towing mileage stayed the same because the lower gear allowed him to stay in OD more often and 70% of 4.10 is way better than 3.73 1:1... And he said the truck runs a 100% better all around.

I think he payed right at a 1000 bucks installed for both sets of gears (front & rear), installation kit and labor. I forget what he paid for the 87 octane tune, but he says it's a totally different truck and he lives in the hill country of W.Va.

What you have to do is buy 2 sets of gears one set for the front and one for the rear...unless your truck is 2wd, if it is, then knock off about 400 bucks. Have someone install said gears. After the install or during have the PCM reprogrammed for your 87 octane tune and make sure you tell whoever does the programming about the gear change so they can account for that. If you opt to not do the 87 octane tune, you will still have to have the PCM reprogrammed for the 4.10s.....any good hand held tuner can make this change. And that is purty much it.

If it were mine, I would consider a professional tuner like Westers or pcmforless, etc. They will know of little "extra" tweaks that can really help not only your engine but the trans also to work better.
 

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Discussion Starter #9
thanks hauler,
your reply was very informative and helpful, how do i go about getting ahold of westers? and do i jsut send off my pcm or whatever tell them i'm running 87 octane an i want the best hp and mileage i can posible get? and they take care of the rest? iono i've neve done anything like this before so anything else you could add would help alot, thanks again.

christman
 

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I have 4.10 gears in my 2005 1/2 tonner company truck, and I am going to go back to 3.73's on my new 07. The 4.10's are okay, but I think they are little low for most driving. I don't tow with that truck, so most of my driving is highway miles, and at 80, it runs 2500 rpm down the road. I get 15 to 15.5 all the time. I could do better with 3.73's. That is a lot of money to spend to switch the gears, I would think about that one. IF you have 3.73's, you will go up about 250 rpm or so going with 4.10. I have driven 80,000 miles with that setup, and I am going back to 3.73's on the next truck. Seems like I am waisting rpm for no real reason.

A good tune will help. I think I went to Westers.com and found those guys. They will walk you through the procedure of how to select what you want and getting another ecm to use for the tune and all that. I have talked to them, and they seem like they know their stuff. Talk with Lyndon, number 888-wester1
 
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