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2015 Nissan Altima - Straight pipes

If i run a straight pipe on my car is something bad going to happen to it??

So, your plan is to delete the catalytic converters and other emissions and noise control hardware? The most likely damage might come from your neighbors.

Several things could happen. You will get a ticket for loud exhaust and one of your neighbors might slash your tires.

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And the O2 sensor/feedback loop would be all messed up, who know how it would run. If your talking about removing the cat, that is.

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So a straight pipe to replace just the muffler? Nothing bad will happen except the increased noise - which I figure is the point of the straight pipe. It won’t make any more power nor will it make your car faster, just louder.


Think long and hard about this…

… and then think again…

Isn’t backpressure important to engines these days? I guess you do not have inspections, I think it would throw a cel at least.

Who might then report you to the local police who would send you to a test center where you would be fined for disconnecting the factory emissions control system.

Don’t do it unless you live on a remote ranch in Arizona and don’t set foot in town.

No nothing bad will happen, the pipe doesn’t care if it’s straight or has a curve in it.

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Or live in an area that doesn’t do emissions testing. I drove around a cat-less/mufferless Bronco around for 6 years. Passed state inspection ever year. The place I used just said that as long as the exhaust pipes exited the vehicle behind the driver’s seating position, it was legal.

It isn’t backpressure so much as it is resonance damping. It’s resonances that cause straight pipes to cause holes in the engine’s torque curve. A muffler, in addition to reducing noise, also damps the standing waves that form in straight pipes at certain rpm’s.
The fact that engines have s broad and seamless torque curve when muffled makes a lot of people assume that engines “need backpressure”.

Probably ok damage-wise to your car. But if you keep the cat, and eliminate the muffler, that configuration might result in bits of backflow from the cat matrix getting sucked into the cylinders. As posted above expect to have nuisance-noise traffic-ticket and emissions challenges to deal with. Those could cost you a pretty penny, so try to be informed what to expect $$-wise on those.

I happen to own 1998 Altima in the past, where the pipe from the cat to the muffler simply rusted through and had a big hole

this car had a little bit of “funny sound”, but it was not to the point where it would irritate either me or neighbors, it was a state inspection where they failed me and I had to finally replace that pipe

Backpressure is used incorrectly or incompletely at times to describe effects of exhaust scavenging. The restriction to flow is an important balance. Creating the right amount of scavenging is important to performance. Too much scavenging is bad from the perspective that the intake charge can get partially scavenged out the exhaust because mechanical valves have overlap.