3.5'' catback

[06 v-maxx]

Is there such a thing as a 3.5'' catback for these trucks without having one custom built? looking for a single side exit behind rear tire.

 

[The_aSSet]

Usually something that big isn't necessary for 80% of builds. 3" would be sufficient like Corsa. But there might be something out there in 3.5"

[06 v-maxx]

Right now i have Dynatech headers & cats but i have the 4.8/5.3 y-pipe setup where they go into one, then 3'' pipe to a gibson muffler then duel 2.5 out.

Its ok but wasnt sure if maby just a single 3'' side exit would be better.

[AKSSS]

If I remember correctly, and stock dura max exhaust is 3.5 inch. They pretty much bolt right on. You just have to weld a couple of hangers on. For my 4" exhaust I used a magnaflow midsection back to the tailpipe for mine. Fit great. Even tucked up nice and tight when I made all new hangers.

 

Forewarned. 3" and up will have serious drone with out the right muffler(s).

[Blown 346]

You will also lose all back pressure and lose power without having a big cubed motor that needs exhaust that size. I wouldnt go any larger than 3" on anything unless it was a serious motor build. I have a 402 in my Camaro thats Procharged and the 3 " exhaust is enough for that. My buddy put a 4" exhaust setup on his 408 Procharged T/A with a F1R Head unit and it hurt his performance. He swapped exhaust over to 3" and picked up 40 some horse.

[AKSSS]

^this is spot on.

The only reason this worked on mine is my turbo. My downpipe is already 3.5".

I have helped a few friends put Duramax exhaust on a few pickups so we coul run large quiet mufflers. They create a lot of back pressure. Lol

[desrtrat]

When discussing performance exhaust systems, it's pretty much common knowledge to the average car guy that too big of an exhaust will rob low end performance. Even more commonly though this is attributed to a lack of Backpressure, which the engine apparently needs to make low end torque.

Now the theory is correct on this, but the term backpressure is very wrong. Backpressure is when there is a restriction or blockage in the exhaust path that causes the flow to revert back onto itself and slow down all flow coming through. It's called backpressure because it's when the exhaust is actually creating pressure back towards the engine.

The term you're looking for is Exhaust Gas Velocity, which is the energy that the exhaust pulse has as it travels from the combustion chamber. The pulse comes out in a wave for each firing of the cylinder. In a average flowing exhaust (no major restrictions or damage) the pulse will create a vacuum behind it that will accelerate the incoming air/fuel charge during valve overlap (aka The Scavenging Effect. So in effect it helps boost the overall volumetric efficiency inside the cylinder because it goes beyond the limitations of atmospheric pressure. If the exhaust is too large for the pulse, than it will slow down and effectively lose the benefits of the scavenging effect along with it.

[kelleyperformance]

we make a 3.5" cat-back and before anyone else asks, no we did not loose any TQ or HP from it is it too much for a primarily stock LSx? absolutely. it was intended and designed for use on 500-750 RWHP builds, but works just fine on 480ish WHP. we have even used this system on a stock LS3 vette with same day dyno testing- gains were seen, no losses anywhere in power bands. yes the LS3 flows a notable amount of more air but still is far from that HP level above... as long as you use the proper size headers and high flow cats, this setup works great. this air velocity as described below is largely related to the header-post cat area being most important.

 

When discussing performance exhaust systems, it's pretty much common knowledge to the average car guy that too big of an exhaust will rob low end performance. Even more commonly though this is attributed to a lack of Backpressure, which the engine apparently needs to make low end torque.

Now the theory is correct on this, but the term backpressure is very wrong. Backpressure is when there is a restriction or blockage in the exhaust path that causes the flow to revert back onto itself and slow down all flow coming through. It's called backpressure because it's when the exhaust is actually creating pressure back towards the engine.

The term you're looking for is Exhaust Gas Velocity, which is the energy that the exhaust pulse has as it travels from the combustion chamber. The pulse comes out in a wave for each firing of the cylinder. In a average flowing exhaust (no major restrictions or damage) the pulse will create a vacuum behind it that will accelerate the incoming air/fuel charge during valve overlap (aka The Scavenging Effect. So in effect it helps boost the overall volumetric efficiency inside the cylinder because it goes beyond the limitations of atmospheric pressure. If the exhaust is too large for the pulse, than it will slow down and effectively lose the benefits of the scavenging effect along with it.

this is good info, but there should still be a small amount of back pressure at the tail pipe if its setup as described. yes back pressure is exactly what said above, yes its usually thought of as bad... but every setup does need a small amount or TQ will suffer as we all said

[AKSSS]

Thanks again Kelley. Knowledgable as usual! Maybe you need to have classes, I would have to fly down from a ways but I could use some more hpt lessons. Lol