I was wandering if anybody is running Dual Straight Pipes and if it sounded cool for Xterras? And is it illegal to not have a muffler or does it vary by state?

Unless you are driving a dropped '63 Impalla it's probably not a good idea.

And yes, it is illegal to completely remove the cats or muffler.

Its only illeagal to remove the cats. the neon SRT 4 dose not have a muffler on it it. Its straight pipe from the cat back.

it really depends.. In this instance yes it is illegal to not have a cat.. But I had a friend who had a 1978 BMW 3 series w/o a cat or muffler and it sounded cherry and the best part was no matter how many times the cops pulled him over they couldn't do anything cause it was legal, that model didn't have cats on.

It is doubtful a cop will pull you over for not having a cat converter. How would they know.. The noise maybe a problem. But you remove the cat and you OBD II is going to go crazy.. You engine will stay on and who knows what else it will do, might not even allow the engine to stay running.

Not true. There are no sensors in the cat converter, thus there will be no error codes displayed (computer wouldn't know it's not there). Oxygen sensors are also mounted in front of the cat most of the time.

Bull Shit.

Here's exactly what there is/isn't, and what the ECU will do about it.

1. There is an O2 sensor before the cats. This is required for engine control and MUST remain in service.

2. There is an O2 sensor AFTER the cats. This is used to tell the computer if the cats are doing their job.

3. If the O2 sensor in #2 is removed, the ONLY negative that will happen is the "Service Engine Soon" light will come on. There is absolutely NOTHING else that will happen to the vehicle and/or engine. The second O2 sensor is strictly to monitor if the cat is doing its job. The only thing that it does if it is not working is light up the MIL. That's it. Nothing else.

4. It is illegal to remove a cat for on-road vehicles. Mufflers are not required unless the particular area you live in has a noice ordinance. They serve no other purpose than noise muffling, and that is not regulated on the Federal level.

I guess I was partly right. I had a VW that was eating O2 sensors and when one would go out the engine ran like shit along with the nice flashing Engine Light.

no worries. There's a lot of misinformation on the 02 sensors and the cats out there.

There are only a handful of people that actually know what happens when you remove them...

Whne I installed the header on my sentra, MY CEL stayed on becuase I had removed the pre cat so the sensors were reading it all messed up.

Porshe996 is right.
I have a 05 with no cats, pertnear straight exhaust. I did install some dynoflow straight through mufflers for tone. The X sounds "SWEET". I race off road with it so it does not matter with the law. My crew says they can hear me coming for a few miles. 5000 rpms from a Nissan 4.0 puts out a distict sound!

By the way I only have the 1st O2 installed right after my header flanges. I get no drivability problems from this set up, other than a check engine light.