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

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wendal

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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...
 

Ilikemtb999

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

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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

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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

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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
1f7ffc682d9b1fd9ec2b193c32c9cdca.jpg

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.
 

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