[83GMCK2500]

Hi Larry, I've read through this thread, the NV4500 swap thread, and the 8.1 install thread for the K10 and I have some questions for you. I'm looking for big block exhaust recommendations/advice and your threads were the first that came to mind. I am past due for exhaust on my '96 and after reading through your threads I recognize you've got a lot of big block experience. If you have the time or inclination to impart any exhaust wisdom upon me, I would appreciate it. If you would like to reply back to me in my thread on my '96 instead of cluttering your thread that works for me.

I've got just under 290k miles on my truck and for the last 20k or so I've had something rattling in the muffler, I assume a weld has broken internally. It's obnoxious and I find it embarrassing.

Ultimately, when this is no longer my daily driver, I'd like to freshen up the engine, rebuild the heads, and put a more aggressive cam in it, injectors, 0411 ECM swap and tune. I would like to replace everything from the manifolds back and I'm considering a dual in/out muffler (unless otherwise recommended), at this time I'm looking at the oval 5x11 Magnaflow mufflers. Unless absolutely recommended I wasn't going to do headers at this time. When the time comes for those, this shop is local to me. I'm open to not replacing the cats, I'm prepared to have it tuned for that (now) or dummy O2 sensors.

The questions I haven't been able to find the answers for: what size exhaust to run on a big block, what kind of backpressure/velocity/flow characteristics are ideal? Do I use two separate mufflers but incorporate an x-/h-pipe before them or is the Mf 5x11 with internal x sufficient? I'm shooting for "not obnoxious at highway speeds" but sounds good if I get on it. I would think that my wheelbase (will take exhaust to behind duals with stock appearance) will help quiet it. With my gearing I'm running ~2,500RPM +/- 100-150 on the highway, depending on speed limit. The muffler is available in/out: 2.5/2.5, 3/2.5, or 3/3. What size do you think is appropriate? In my research to try and find what size exhaust you used on your vehicles I came across your L18 swap resource thread on CK5 and I read about the redesigned cat. converters on the '06+ vehicles. Should I try and source a pair of the new ones? Lastly, I'll be using mandrel bent tubing for the bends.