What did you do to your NNBS GMT900 Tahoe/Yukon Today?

[gooffeyguy]

Mine's not lowered and I don't notice the resonator unless I'm laying looking under the vehicle [emoji848]

2001 Yukon SLT
2012 Yukon Denali XL
2011 Yukon Denali RIP 5/20/18

I take that back, you can see part of the bottom of it behind the rear tire if you know what to look for, but not enough for me to spend any time worrying about it... Lol

2001 Yukon SLT
2012 Yukon Denali XL
2011 Yukon Denali RIP 5/20/18

 

[07Burb]

I take that back, you can see part of the bottom of it behind the rear tire if you know what to look for, but not enough for me to spend any time worrying about it... Lol

2001 Yukon SLT
2012 Yukon Denali XL
2011 Yukon Denali RIP 5/20/18

I guess that depends on the person looking at it. When that dingleberry was hanging there on mine it bugged the crap out of me and had to go fairly quickly. t just looks horrible IMO Then again, maybe I'm psychotic LOL

 

[wendal]

Monkey wrench time!

Any info on tri-Ys?

I too saw Doug Thorley Tri-Y headers on Summit Racing:

https://www.summitracing.com/parts/dte-310y-1-c/overview/year/2007/make/gmc/model/yukon

More than I want to spend on headers, but I will if they will get some gains and meet my other criteria. I may have to be the guinea pig on these...

Anyone else tried / run these?

 

[Sam Harris]

In my opinion...

If you are looking to get every last bit of power out of your engine ABOVE 5000 RPM then long tubes are the way to go.

If you are looking for more power in the 2000-5000 RPM range, where it's more usable for daily street driving, then the JBA Cat4ward headers do a pretty good job. Several of the header companies make headers that all look alike. JBA, Gibson, BBK, Dougs.. etc.

JBA Headers and Exhaust System Give This 5.3L V8 a Power Upgrade
https://www.offroadxtreme.com/engin...ust-system-give-this-5-3l-v8-a-power-upgrade/

Whatever you go with make sure you get ceramic coated and I would also suggest getting a good set of locking header bolts. I went with the Stage 8 locking header bolts found here...

https://www.stage8.com/product/8900-chevrolet-ls1-ls2-ls6-header-bolt-kit/

I purchased mine on Ebay for like $20 though.

Also you need to be cautious when choosing a camshaft. You need to figure out how YOU drive and where YOU want more power.

Keep in mind that these are big heavy trucks and you don't want to sacrifice a bunch of low end torque for the high end horsepower or else it will feel sluggish in normal everyday driving.

Also if you choose too big of a cam you will need to install a different torque converter to really take advantage of the power band.

This is all just my opinion... I am certain others will chime in as well.

Just FYI you CAN get long tube headers with an aftermarket Y-pipe that has cats in them... but all of that will cost substantially more obviously.

I decided to go with long tubes (though I haven’t done it yet), but since I’ve got almost 200k on the clock, and I’m confident the cats are original, I would hate to do shortys, only to find out in 6 months, I need to do the cats too..

 

[Rocket Man]

I decided to go with long tubes (though I haven’t done it yet), but since I’ve got almost 200k on the clock, and I’m confident the cats are original, I would hate to do shortys, only to find out in 6 months, I need to do the cats too..

American Racing longtubes with or without their high flow cats ftw.

 

[wendal]

American Racing longtubes with or without their high flow cats ftw.

@Rocketman , I would love to do these. It's just not financially feasible for me, especially if I'm going to do the Cam and AFM delete. Now, if you'd like to make a significant donation to the cause, I'm all in!

 

[wendal]

@kbuskill , You did the shorties. Did you have to change the Y pipe as well? If so, which did you use? I'm looking at the JBA's, Gibsons, and Pacesetters. Other than the JBA's, which @kbuskill has covered thoroughly, anyone have any feedback on these manufacturers? The Pacesetters are the most cost effective, @ $320 on RockAuto, before the forum discount. From the entry on RockAuto:

PACESETTER 72C1346 C.A.R.B. Compliant; ARMOR Coat Performance Header; Incl. Gaskets And Hardware; Shorty Header Info
1-5/8 in. Tubing Dia.; 2-1/2 in. Collector Dia.; CARB E.O. D-439-9; Flanged Collector; Replaces Stock Exhaust Manifold; Bolts To Stock Down Pipe; Retains Catalytic Converter In Stock Location

$320.79

ARMOR*COAT- LOWER UNDERHOOD TEMPERATURES

Keep underhood temperatures to a minimum and protect your investment! Pacesetter's ARMOR*Coat finish is a polished, 2000 F metallic ceramic coating. ARMOR*Coat won't discolor like paint, chrome or even stainless steel. It reduces underhood temperatures, helps the header resist rust and corrosion and is easy to keep clean. The coating itself is guaranteed not to chip, peel or flake for three years.
***********

I'm inclined to go with these, as they are by far the most cost effective, unless I hear from you guys that they are crap, or that they don't perform well.

Please let me know what you guys think!

 

[Ilikemtb999]

I have speed engineering long tubes hanging on my garage wall that I coated in high temp cerakote. Still need to order some cats for it.

 

[kbuskill]

I did not HAVE to change the Y-pipe.

I chose to remove the cats and I lost some torque so I had a new smaller diameter Y-pipe built to restore the lost torque.

 

[swathdiver]

@kbuskill , You did the shorties. Did you have to change the Y pipe as well? If so, which did you use? I'm looking at the JBA's, Gibsons, and Pacesetters. Other than the JBA's, which @kbuskill has covered thoroughly, anyone have any feedback on these manufacturers? The Pacesetters are the most cost effective, @ $320 on RockAuto, before the forum discount. From the entry on RockAuto:

@badandyturbo

 

[wendal]

I did not HAVE to change the Y-pipe.

I chose to remove the cats and I lost some torque so I had a new smaller diameter Y-pipe built to restore the lost torque.

That's right, I read that. Sorry for the repeat. I have been searching the internet, and can find no reviews, nor videos featuring the Pacesetter Shorties. Everywhere that sells them, no reviews are present. I guess NO ONE with a computer/phone has used them, or no one wants to say so... scary... I don't want to be the guinea pig for the entire automotive world... May go with the JBA's like you, @kbuskill . At least I know what I'll be getting...

 

[kbuskill]

Received my Gruven heater core T-connectors and Dorman Y-connector today...

Its gonna be next weekend before I can get them installed.

 

[Ilikemtb999]

I’d think as an aerospace engineer, Paul would provide spring clamps not work clamps. The Y’s look great though

 

[wendal]

anyone know anything about BBK?

https://www.amazon.com/BBK-40050-Pe...-4&vehicleName=2007+GMC+Yukon#customerReviews

 

[kbuskill]

anyone know anything about BBK?

https://www.amazon.com/BBK-40050-Pe...-4&vehicleName=2007+GMC+Yukon#customerReviews

They are 1 3/4" primary tube VS the JBA 1 5/8" primary tube.

The smaller the pipe, the faster the hot gases will flow out.

The larger the pipe, the slower the hot gases will flow out.

The smaller pipe cannot flow as much volume but it will scavenge better due to the gases moving faster.

The larger pipe will flow more volume but at slower speeds which will reduce the scavenging and not produce as much power down low.

With exhaust, and headers especially, it's about keeping the gases hot and moving as fast as possible.

Hot gases expand and flow faster than cold gases.

You don't want "back pressure" but you also don't want a huge wide open pipe because when the hot gases leave the head they will expand to fill the larger pipe which will slow them down which kills the scavenging.

You want the hot gases to escape into a smaller pipe so that less expansion takes place and the gases will maintain there velocity/momentum and create more of a vacuum effect on the other cylinders... = scavenging.

A naturally aspirated 5.3L doesn't need anything bigger than 1 5/8" header.

 

[iamdub]

There’s a giant muffler/res right in the middle. Not the very end bit.

Interesting. Apparently, I've always overlooked that.

 

[iamdub]

I too saw Doug Thorley Tri-Y headers on Summit Racing:

https://www.summitracing.com/parts/dte-310y-1-c/overview/year/2007/make/gmc/model/yukon

More than I want to spend on headers, but I will if they will get some gains and meet my other criteria. I may have to be the guinea pig on these...

Anyone else tried / run these?

From everything I've read, they're a good blend of both styles. It's how NASCAR headers are, except they're tuned for power in a narrow RPM band for obvious reasons. When I can't swing one way or the other, I tend to aim for right down the middle. Although, with the low-RPM torque benefits of shorties, there may be more mid- and upper- RPM gains to be had by deleting the cats. Seems to me this would be a close second to tri-Ys.

 

[iamdub]

I take that back, you can see part of the bottom of it behind the rear tire if you know what to look for, but not enough for me to spend any time worrying about it... Lol

2001 Yukon SLT
2012 Yukon Denali XL
2011 Yukon Denali RIP 5/20/18

That's not very obtrusive at all. For us with the 5.3, the exhaust exits out the side, making the side of that giant can really visible from the back.

 

[Rocket Man]

@Rocketman , I would love to do these. It's just not financially feasible for me, especially if I'm going to do the Cam and AFM delete. Now, if you'd like to make a significant donation to the cause, I'm all in!

Check’s in the mail.

 

[iamdub]

Check’s in the mail.

Had to Google "check". *sigh* You're one of THOSE.

I guess you holding up the line at the grocery store as you fill out your check is still way faster than you counting out your change to the cashier.