2003 Silverado 4.8 performance question...

[djv72]

I just purchased this truck with 400 miles on it. It's an extended cab, standard box, 4x4 with a 373:1 rear end. I couldn't stand how quite the truck was so, I went to the muffler shop and had them install a Flowmaster 40 Series muffler. I did not add dual exhaust. They just cut out the old muffler and installed the flowmaster. Now, I have only had the truck for a week when I did this. My truck seems to be slow from a dead stop (ie. won't even turn over the tires). If I get on it at 25MPH, the truck moves.

A friend of mine has a 99 Silverado, 4.8, 4X4, Reg cab, Short box with 33" tires on it. I race him from a stop light and he kicked my butt off the line and I caught him with no problem.

Anybody have any ideas if I need to reprogram the computer since I changed the exhaust? Did I hurt my performance?

I didn't buy this truck to race it (I have a Mustang for that) I am just disappointed in the power off the line.

Thanks,
Dan

[digdug1]

yeah i have the same problem in my 99 ext cab.it has the 5.3 in it though. off the line i got nothing, it wont even spin a tire!!
i took it to a shop and got a single in dual out flowmaster with turndowns but i got nothing. whats wrong? is this normal? what can i do to correct this?
any help would be appreciated!!!!

[djv72]

My friend has a 2001 Silverado ext cab 5.3 and that thing runs like a raped ape! I can't believe that people will read my post but, won't respond.

Dan

[Spiderlad]

I just got a 2k3 Silverado 1500, ext cab, Z71 with the 4.8L currently stock and I couldn't get the tires to squak off the line from a stand still unless I cheated. My dad has a 2k1 1500 with the 5.3, identical everything else and I can usually get that to give me a little bit of noise if I try. When I asked one of the mechanics from the dealership that I bought the truck from when I was deciding between the 4.8 and 5.3 ($$$) he had told me that there was only a 15hp difference between the two engines but the amount of torque that the 5.3 had was greater than the 4.8 so from what it seems if you want to get it to make some noise you'll have to do some performance enhancers.

[thor48]

Originally Posted by Spiderlad

I just got a 2k3 Silverado 1500, ext cab, Z71 with the 4.8L currently stock and I couldn't get the tires to squak off the line from a stand still unless I cheated. My dad has a 2k1 1500 with the 5.3, identical everything else and I can usually get that to give me a little bit of noise if I try. When I asked one of the mechanics from the dealership that I bought the truck from when I was deciding between the 4.8 and 5.3 ($$$) he had told me that there was only a 15hp difference between the two engines but the amount of torque that the 5.3 had was greater than the 4.8 so from what it seems if you want to get it to make some noise you'll have to do some performance enhancers.

something must be wrong with your z-71. my base 2003 4x4 silverado 4.8 will bark the tires at 30mph when i floor the gas.It has 3.73 gears and heavy duty suspension pkg. and trailering pkg. thor48

[Spiderlad]

Hmm, I can tell it comes close to squak'in but it doesn't, I do have the bigger tires on it (can't remember which package that came with) so who knows, I'm probably going to do a few mods to get the HP up but then I'm planning on eventually Lifting it and throwing on bigger tires so who knows what it'll be able to do eventually, I'm not too worried about it, I can keep up with some of my buddie's cars and whoop all their trucks so I'm currently satisfied

[Vic Vega]

weird if i mash the pedal on my 04 4.8 from a dead stop it will chirp for a bit and if i dump the clutch at 3k it will smoke through 2 almost three gears the difference...... I have a manual transmission. I really want one of those volant ram air filter boxes
but to answer the question try starting your auto trannie in first because by default auto boxes like starting in a higher gear (for best gas mileage)

[Joshs2002Silverado]

i dunno...i got a 2002 extended cab silverado..and if turn my traction control off i can spin the tires smoke the shit out of my tires....lol...but then again i have done a few performance mods....i put flomaster exhaust, k & n cold air intake, hypertech programmer and a beautiful set of edelbrock header....im gonna go dyno my truck soon to find out what the rear wheel hp is....but it spins em off the line....
josh

[Joshs2002Silverado]

i dunno...i got a 2002 extended cab silverado..and if turn my traction control off i can spin the tires smoke the shit out of my tires....lol...but then again i have done a few performance mods, and i have a 5.3....i put flomaster exhaust, k & n cold air intake, hypertech programmer and a beautiful set of edelbrock header....im gonna go dyno my truck soon to find out what the rear wheel hp is....but it spins em off the line....
josh

[Lockjaw]

I have a 2000 model Standard cab, short bed with a 5.3, and it did not spin tires at all when I first got it, after some time on the engine, about 30k, it will light them up if I want to.

I want a higher stall converter, I think that will help.

[gtlegacy]

What kind of rear end do you have? If your friend has the factory diff w/out limited slip he is going to screech the tires way easyer than if you have the factory limited slip. I have a 99 5.3 with 33's and if you hold the brake and give it quarter throttle then let off the brake and flore it it jumps off the line...you should try that. I was sick of the 33's bogging my truck so i put 4.56's and an Auburn locker in the back. WOW what a difference. I can burn out till my tires pop. I have yet to take it on the quarter mile, i know i would give those rice burners a run for thier money. The Hypertech, intake, and exhaust helped alot. When i stiffend the tranny with the chip it made it so i could chirp second gear with an automatic. Before looking at getting engine mods you should consider 4.11 cause who needs to go 150 on the freeway anyways; and plus your truck has a top speed limiter.

[The Ladies Man]

i have a 2000 gmc sierra with a list of stuff done to it and with 3:73 i cant spin the tires at all, it sorta dogs until like 1700 rpm then take off like a raped ape!!! i also have the factory locker. not sure i had the extra money i would like to put 3:85 or 3:90 gears in just for the extra off the line jump

[gtlegacy]

if your going to go through the trouble of putting gears in go with 4.11s. I just ran a 7.5 second 0-60 with my truck. I have a k&n intake flowmaster exhaust and a hypertech chip. The 4.56s are equivilent to 4.11s on my truck because i have 33 inch tires. I still get 13 -15 mpg.

[theidbreder]

I have a 2003 Z71 5.3 and I have had no problems spining the tires or getting good jumps off the line. I put a 40 series flowmaster, AEM Brute Force cold ait intake, Mass air flow sensor, Bosch platinum 4 spark plugs on it and that thing has no hesitation or lack of power at any time. I wouldn't been able to do it stock , but my 5.3 has beaten my friends HEMI several times when we line them up. I saw the best results form the intake and the Mass air flow sensor, but believe it or not the plugs made a big diffrence and it is a cheaper route to go fo a quick 7hp at the wheels.

[The Ladies Man]

Originally Posted by theidbreder

I have a 2003 Z71 5.3 and I have had no problems spining the tires or getting good jumps off the line. I put a 40 series flowmaster, AEM Brute Force cold ait intake, Mass air flow sensor, Bosch platinum 4 spark plugs on it and that thing has no hesitation or lack of power at any time. I wouldn't been able to do it stock , but my 5.3 has beaten my friends HEMI several times when we line them up. I saw the best results form the intake and the Mass air flow sensor, but believe it or not the plugs made a big diffrence and it is a cheaper route to go fo a quick 7hp at the wheels.

What rear end do you have and is it extended cab. because i am waiting for the day the hemi happens to stop next to me a light!!!