Dual 3" exhaust?

[Drewu223]

They used the same 3" pipes on 350s and 6.0Ls. The trucks are actually 2.75". The vans are 3".

Did all trucks come with 2.75"? I measured mine with a caliper just for ***** and giggles and it was a 3" pipe. Unless someone changed it before my grandpa bought the truck

 

[89obsSB]

May want to do some more research before loosing any torque especially if you tow a tractor.

 

[Drewu223]

May want to do some more research before loosing any torque especially if you tow a tractor.

It'll be alright. I'm in the process of a 96 7.3 F-350 dually build to tow all my toys with, the Chevy is gonna be my weekend cruiser. Call me a child if you want but I'm just trying to get more noise without just going open headers haha

 

[89obsSB]

It'll be alright. I'm in the process of a 96 7.3 F-350 dually build to tow all my toys with, the Chevy is gonna be my weekend cruiser. Call me a child if you want but I'm just trying to get more noise without just going open headers haha

Everything I’ve ever owned has been loud other than a couple family vehicles. Acadia and envoy in the past.

 

[Drewu223]

Everything I’ve ever owned has been loud other than a couple family vehicles. Acadia and envoy in the past.

I unbolted the exhaust from the cat back on my daily 2013 Nissan rogue haha. Only did that for a couple months cause with a cvt it sounds like trash

 

[RichLo]

I was surprised when I first saw that. I was laying under the truck one day looking at something and realized it went from the 3" head pipes into the cats, then from the cats back it was 2 1/2" for a few feet then into 2 1/4" tailpipes. Talk about being necked down.

My 97 dually is the same way... I just thought it was because they used the factory muffler-back piping and slowly stepped it down when they re-did the manifold-to-muffler exhaust. I'm going to put 3" glasspacks with turndowns under the bed on it to get rid of that necked down BS.

 

[Supercharged111]

Did all trucks come with 2.75"? I measured mine with a caliper just for ***** and giggles and it was a 3" pipe. Unless someone changed it before my grandpa bought the truck

My dually is 3" into the cat and 2.75" out. As the exhaust cools toward the back of the truck, it needs less pipe to flow. That said, cats don't cool the exhaust, so I'm confused by GM's logic here.

 

[L31MaxExpress]

My dually is 3" into the cat and 2.75" out. As the exhaust cools toward the back of the truck, it needs less pipe to flow. That said, cats don't cool the exhaust, so I'm confused by GM's logic here.

Van was and still is dual 3 to the muffler. Looks big even compared to the 2.75" truck stuff. Huge pipes compared to the ones on my 99 Tahoe. 99 Tahoe was a dog though. Factory to factory the van came close to being able to outrun it despite being 1,000 lbs heavier with the same trans and same rear gear. The 99 Tahoe was pretty detuned though and had an EGR diffuser that was 2x as wide as the vans. Factory Tahoe tune had 6-8° less timing at WOT down in the 1,000-2,800 rpm range too. Removed the diffuser lip and gave it a good tune and the Tahoe came alive though even with the small pipes.

 

[Supercharged111]

I lined up the crew cab flipper dually, 454/4L80 with a 350/4L60 1500 ECSB and it got SMOKED. Truck felt like a turd so this exercise was a sanity check. Dude that bought the truck was super happy with it and another friend I let drive it said it felt great.

 

[L31MaxExpress]

Never understood why the vans had a resonator in front of the RH cat either. Pictures of a virgin exhaust on a van I parted out. Identical to my 97. The Thorley headers have a long extension to replace the smaller pipe after the manifolds on the driverside as well as eliminate the resonator on the passenger side. When we rebuilt my exhaust we swapped the cats left and right for added clearence for the added length of the dual 3" inlet/single 4" outlet bus muffler and I re-pinned the rear 02 sensors to match. BIG difference in torque after the headers, high flow cats, bus muffler and retune for it all.

You must be registered for see images attach

You must be registered for see images attach

You must be registered for see images attach

1

You must be registered for see images attach

You must be registered for see images attach