8.1 Exhaust systems

[CMNTMXR81]

Ok, I'm in a quandry.

Borla and Gibson both make cat-back systems for the 8.1. Problem is, the Borla I'll need to bend over and take up the exit ramp for and it's not what I really want. The Gibson just isn't the style I want.

I was originally going to take my stock system off, plumb two mufflers 2.5" (either DynoMax or Magnaflow, whichever fit better) and go out through 2.5" pipes with 3.5" tips on it coming out between each rear wheel.

However, I have been thinking that I may choke the 496 too much with this setup.

No one out there has a 3.5" or 4" to fit the big block with the piping to match. Magnaflow makes a diesel system for the Duramax that is 4", but it only has one inlet pipe, so that won't work with the 496.

What to do? I want to keep it a minimum size of the stock 3.5" system but I have yet to find anything that will work.

[99GMC]

What about the dual setup with 3.5" or 3" pipe? I thought a few of the aftermarket mufflers were 3"?

[CMNTMXR81]

I may do that as a last resort. I see Magnaflow makes some 3" in/out mufflers and I can't get my Adobe to work here to download DynoMax PDF files.

[BC Rod and Custom]

go to a custom exhaust shop and have them build you a muffler.

[rollinstyle]

I don't know if it makes a difference, but they have 4" in/out diesel mufflers. I don't know if the muffler is different for gas and diesel, but I thought I would tell you.:confused:

[Dubyagee]

Originally posted by z-71rocks
go to a custom exhaust shop and have them build you a muffler.

i agree I paid 250 and some change for mine....cant be much more for yours

[BC Rod and Custom]

i paid about 450 installed for my whole system from the cats back including crossover.

[tweaker]

My local high perf muffler shop only replaced the OEM muffler with a dual 3"in/dual 3" out Magnaflow. They reused the OEM 3" Y into the 3.5" OEM tail pipe. It made a HUGE difference in performace all the way through the power band. I couldn't belive what a difference it really made. The only bummer was that it resonated too much with the 6.0L. It was LOUD too, which I didn't mind. I understand the 8.1 won't resonate like the 6.0L as the 3" dual tubes & 3.5" tail pipe match the exhaust flow better.

For my 6.0L, I necked the 3" pipes down to 2.5" about 2' before the muffler and am using a dual 2.5" in/dual 2.5" out Magnaflow with dual 2.5" tail pipes out each side now. That solved my resonation problem for the most part. Before that, I tried a dual 2.5" in/single 3" out Magnaflow with a 3" single tail pipe. It sounded tuff and cured a lot of the resionation problem, but seemed to choke the 6.0L above 3,000 rpm. 1,200 to 3,000 rpm was great. The dual 2.5"in/out is a perfect fit for the 6.0L for good all around performance. I think this would be too restrictive for the 8.1L.