Does Removing the Cat Converter Cause Problems with Engine Computer, etc.?

[utah smitty]

I just bought a 2000 Chevrolet 3500HD with a VIN code F 6.5 TD, and California emissions. It has the stock exhaust system, which has had pieces added/repaired by the previous owner (an HVAC Company with a bunch of trucks).

In addition to the muffler, there is what I assume to be the Cat Converter upstream closer to the turbo.

I live in Utah, and there's no emissions required on this truck because it's GVWR exceeds 14,000 lbs.

I want to install a 4" exhaust, but I'm concerned that not having the Cat Converter might cause problems with the ECM?? or other engine-based computer.

Can anyone enlighten me on this?

Thanks,

Smitty5825

[DmaxMaverick]

If it has a cat, it won't cause issues removing it. Until DPF came along, they weren't monitored. However, it may not be a cat, but likely a resonator. Look at the intake for an EGR (will be a large valve right in the middle of the manifold inlet). If it has EGR, then it has a cat (and therefore, an S code). Although, I'm not aware of any 2000-ish CA trucks with a GVWR greater than 8600# with any of that. Mine is a 2001 Duramax and doesn't have it. None of the GMT-400, 3500HD should have any smog equipment. The late model 3500HD does, but it's not nearly the same animal (rebadged light truck 1-ton). The 3500HD you have is, in fact, a medium duty truck. In CA, the smog rules never applied to the class until very recently. If, for any reason in CA, an L56 engine was installed in place of the original L65, the law requires that all the smog equipment to follow. I don't know of anyone or company that would abide that, but it is the law, and I'd have no idea why anyone would do that, anyway.

[utah smitty]

If it has a cat, it won't cause issues removing it. Until DPF came along, they weren't monitored. However, it may not be a cat, but likely a resonator. Look at the intake for an EGR (will be a large valve right in the middle of the manifold inlet). If it has EGR, then it has a cat (and therefore, an S code). Although, I'm not aware of any 2000-ish CA trucks with a GVWR greater than 8600# with any of that. Mine is a 2001 Duramax and doesn't have it. None of the GMT-400, 3500HD should have any smog equipment. The late model 3500HD does, but it's not nearly the same animal (rebadged light truck 1-ton). The 3500HD you have is, in fact, a medium duty truck. In CA, the smog rules never applied to the class until very recently. If, for any reason in CA, an L56 engine was installed in place of the original L65, the law requires that all the smog equipment to follow. I don't know of anyone or company that would abide that, but it is the law, and I'd have no idea why anyone would do that, anyway.

Ok, thanks. I was mainly concerned about potential problems with the engine if I removed whatever it is. Utah doesn't require emissions on medium duty trucks. Anyway, here's a picture of whatever it is:

5828

Now I just need to order an exhaust system...

Smitty