cutout question

Im thinking of getting a cutout on my 99 silverado 5.3 ltr, is it as simple as welding it in and running the wiring, or will there be any issues with sensors?

Im thinking of getting a cutout on my 99 silverado 5.3 ltr, is it as simple as welding it in and running the wiring, or will there be any issues with sensors?

Well, kinda both. It is as easy as welding up the cutout, then putting on the electric plate and running the wires. You will have to do one of two things about the rear 02 sensors..
1. get a custom tune to remove the sensors from the pcm
2. get a set of 02 simulators to plug into the rear to fool the pcm into believing everything is ok.

will it still run the same?


-ive seen the vid of your truck, very niiiice!

You could also just mount the cutout after the o2 sensors and not have a problem. If you want to bypass your cats then need to go with one of slowprocess's suggestions. As for the truck running different, my truck runs noticeably stronger in the higher rpm band when the cutout is open.

You could also just mount the cutout after the o2 sensors and not have a problem. If you want to bypass your cats then need to go with one of slowprocess's suggestions. As for the truck running different, my truck runs noticeably stronger in the higher rpm band when the cutout is open.

I noticed an increase in the upper rpm range as well. My 1/4 times are still pretty consistant with them open, but I do get alittle higher mph with them open. It seems to loose a small amount of low end torque with them open, but not enough to be that noticeable.

Yeah, I definitely agree with you ont hat slowprocess. When they're open I can definitely hit higher speeds quicker.
Slowprocess: Have you noticed any difference in mileage with the cutouts open vs. closed?

Yeah, I definitely agree with you ont hat slowprocess. When they're open I can definitely hit higher speeds quicker.
Slowprocess: Have you noticed any difference in mileage with the cutouts open vs. closed?

I usually don't ride with them open enough to be able to make a comparison. I just hit the switch when I want to mess with somebody, or if I'm at the track. My truck is pretty much a gas HOG as it is with the setup I'm running.(Well, only when I'm getting on it, which is pretty much all the time. :biggrin: )
What kind of results have you seen in gas mileage differences?

hey air how do they sound on the 5.3ltr?

Well first off I won't be 100% sure until next week about my mileage because I only recently began measuring it and my cutout is still open. Last week I noticed that a full tank seemed to disappear a hell of a lot quicker than normal even though it never lasts for long the way i drive. At first I just attributed it to the way I was driving and I realized the cutout definitely had an effect. It may just be b/c whenever my cutout is open I just really want to get on it. There is a noticeable increase in power felt "in the seat of yuor pants." The truck just seems to GO when I hit it. But i have noticed a loss in low end torque with them open so i figure that it may take a bit more power to get the truck moving at low speeds. I do a bit of offroading and last week was a rainy one here in dallas so I was pulling people out of the mud right and left. With the cutouts open I definitely needed to give it more gas in the mud where i normally would have only gone slightly above idle. once they were closed the truck seemed to have more pep in the low end but lacking up high.
As for sound, I am sure that slowprocess willa gree that it sounds amazing with cutouts open. It sounds like a '69 camaro running straight pipes when you get on it and the idle is nice and choppy but not too loud. I'm sure you'll love it but you'll also love the electric cover because it can get real loud for everyday driving. Tomorrow after I fill up the tank i'll keep them closed until the next fill up so I can get a good comparison of mileage.
Sorry for the rant, i'm just a bit wired...