H3 High flow or cat-less intermediate exhaust?

[Dyno Dan]

Did any of the mainstream exhaust manufacturers product high flow or cat-less intermediate pipe? I’m referring to the section between the manifolds and the cat-back section. Does anyone have a cut open / cross section of the pre-cat relative to the post-cat? Just curious on their internal contruction and if there is a potential gain in power from removing one or both from each side......***if they were ever damaged for any reason***

 

[alrock]

A good muffler shop can fabricate the intermediate pipe. There's definitely a sound change from the removal of the secondary cats. While I'm not aware of any high flow cats for the H3, you can use any cat that fits and there should be plenty.

 

[amrg]

I used magnaflow high flow cats and removed all oem units. Definitly big difference in the sound department. Iirc I read somewhere that the main reason the trucks that had the 5.3 back in 09 had 20 more hp than on the Alpha was due the restrictive exhaust (the alpha had 4 cats, 2.5" pipe as opposed to 1500 series 2 cats and 2.75" pipe)

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[Dyno Dan]

Happen to have any pics?

 

[Ordieh]

I used magnaflow high flow cats and removed all oem units. Definitly big difference in the sound department. Iirc I read somewhere that the main reason the trucks that had the 5.3 back in 09 had 20 more hp than on the Alpha was due the restrictive exhaust (the alpha had 4 cats, 2.5" pipe as opposed to 1500 series 2 cats and 2.75" pipe)

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And the smashed in inefficient crossover. I was told this by a GM engineer.

 

[Lauren]

My cats died.. so I took them out and just replaced it with a "Y Pipe".
Had to get it made though because we couldn't find one that was the correct shape.. but we are having a small issue because finding the correct seal is proving a little difficult but its alright.. the noise from the gap isn't too loud

Anyway! Sound is a little different but I found that she responded a little better too!

Now I've changed the back muffler to a magnaflow one and had her tuned.. much much better!

 

[dobbner]

I also replaced my rear muffler with a Magnaflow that I bought from 4wheelonline. It sounds much better than stock. No drone inside my rig.