What exactly is a cat back exhaust? Doesn't it delete the catalytic converter and mufflers? Is it legal to use on all vehicles? And can it be used on a gas truck or is it just for diesels?

 

A cat back is exactly as it sounds, it replaces everything from the catalytic converter back. It doesn't replace the actual cat, just the pipe that bolts to it back to the rear exit pipe. I don't know how it is in the truck world, but how it is in the muscle car world is as follows:

Manifold back exhaust - keeps factory exhaust manifolds and replaces everything from there back. Some kits include the cats, some do not. The ones that do not are called off-road systems (since you're not legally supposed to run them on public roads).

Cat back exhaust - keeps factory manifolds and cats, but replaces all the exhaust piping from there back. Usually this is what most people do to keep their vehicle 100% street legal.

And then you have aftermarket headers and their Y-pipes / X-pipes / and H-pipes that get your exhaust into any configuration you could dream of.

 

I live in Montana and I'm not exactly sure what the laws are up here but I do know they don't do any emissions tests. Would I be able to get away with a manifold back then? I have a Ram 2500 with the 8.0L V10 and I want it to have a really deep rumble sound to it.

 

If Montana is anything like Texas, you probably would still have to pass a visual inspection. I'm not sure if they offer any manifold back systems for our generation Dodge Ram, but I've seen a ton of cat backs for it. If you have a hook up with someone with a welder, you could always cut the exhaust right after the cat, use a pry bar to gut the cat, and then have the pipe welded back up. That way you still pass the visual inspection. That's what I have done on my Firebirds and I pass every time.

Just as an side, if you do gut or remove the cat then you're going to need an O2 simulator for the rear O2 sensor so you won't throw any codes or have any issues with your truck running poorly since the ECM uses that data to measure precise fuel / air mixtures. The front sensor will be fine, it's just the rear one you have to worry about. For my Firebirds I just had my cousin tune them out with software that he has, but many other people just use simulators with no ill effect.

 

There is no reason to remove a CAT unless it's clogged.

 

Does removing the CAT give it a deeper sound? Or is the CAT completely irrelevant when it comes to the sound of the exhaust?

They don't even do visual inspections up here but I'm in the military so eventually I could move to a state that does. Hopefully I'll get to go back to Missouri (that's where I'm from) but they don't do emissions tests either so that's not gonna be an issue either way.

 

The cat makes your exhaust quieter.

 

ive got a magnaflow catback on mine and it was pretty nice sounding, it wasnt until i paired it up with some borla headers that it started sounding like a monster. keep the cat, be kind to the enviroment.