Long Tube Headers + Stock Catalytic Converters

[ogdrew]

Hi all,

I'm interested in purchasing a set of long tube headers for my 2013 ZL1 6M. They would be 1 7/8, from speed engineering. The issue is that I don't want a lot more sound, I'd like to keep the sound low, and to fix that, I'm hoping to stick with stock catalytic converters. I'm looking to get the power gains from the headers, but the loudness staying the same.

Has anyone done this with long tube headers? Is this possible? If it is, let me know how you did it (pics would be nice too ).

Thanks,
Drew

[Shodown]

You're going to spend more money in fab work cutting and welding the the stock cats rather than just buying aftermarket cats that are plug 'n play with the long tubes. Plus you won't gain much power putting them back on because they are so restrictive.

[prod]

Most go with hi-flow cats in your situation. They flow better and sound better without the rasp of going catless.

[ZMEnow]

Originally Posted by prod

Most go with hi-flow cats in your situation. They flow better and sound better without the rasp of going catless.

You will only notice loudness when you cold start and when you go wot as the NPP will keep the stock sound till it opens and bi passes. The stock cats are the most restrictive part of the exhaust system, besides all the remanufacturing required and cost for that as mentioned in the thread.

[ogdrew]

Noted- thanks for the input.

I believe the setup I'm going to go with is as follows:
Speed Engineering 1 7/8 LTH,
& 3 inch ZZPerformance 400 cell catalytic converters. They also claim to be "high flow" but I'm not sure how accurate that is.
Does anyone know of any direct bolt on high flow cats to the speed engineering headers? 3 inch + 400 cell would be preferred.

Thanks,
Drew

[SSammy]

Originally Posted by ogdrew

Noted- thanks for the input.

I believe the setup I'm going to go with is as follows:
Speed Engineering 1 7/8 LTH,
& 3 inch ZZPerformance 400 cell catalytic converters. They also claim to be "high flow" but I'm not sure how accurate that is.
Does anyone know of any direct bolt on high flow cats to the speed engineering headers? 3 inch + 400 cell would be preferred.

Thanks,
Drew

Just my opinion, but many shops have tested and stated that the stock cats on our cars are a big restriction. 400 cell cats are still pretty restrictive, and I believe many OEM cats are around 400 cell, so I wouldn’t consider them high flow. I installed 200 cell cats behind long tubes and have never thrown any codes for catalyst inefficiency. Your mileage may vary. I felt like 200 cell were a decent compromise. You can still keep the noise levels down with muffler choice (moderate or mild axle back) without choking the exhaust flow with 400 cell cats.

[ogdrew]

Originally Posted by SSammy

Just my opinion, but many shops have tested and stated that the stock cats on our cars are a big restriction. 400 cell cats are still pretty restrictive, and I believe many OEM cats are around 400 cell, so I wouldn’t consider them high flow. I installed 200 cell cats behind long tubes and have never thrown any codes for catalyst inefficiency. Your mileage may vary. I felt like 200 cell were a decent compromise. You can still keep the noise levels down with muffler choice (moderate or mild axle back) without choking the exhaust flow with 400 cell cats.

I'm not worried about throwing any codes, I'm worried about the sound. I'd rather not have the car be obnoxiously loud which I why I chose 400 cell cats. I have the stock cat back and am trying to find a compromise with the new LTH + cats (not sure cell count yet, debating between 300 and 400) to keep the noise generally stock but also give me that power that can be gained from high flows.

Thanks,
Drew

[Coop[580]

Maybe a Honda Accord is more what your looking for..... nice a quiet but yet peppy...... but really the power your gonna get is minimal from exhaust. The responsiveness is what you’ll notice a little more..... the sound is why I believe many do exhaust mods. Opens the car up. Breath better!! .

[ogdrew]

Originally Posted by Coop[580

Maybe a Honda Accord is more what your looking for..... nice a quiet but yet peppy...... but really the power your gonna get is minimal from exhaust. The responsiveness is what you’ll notice a little more..... the sound is why I believe many do exhaust mods. Opens the car up. Breath better!! .

Haha, if only it was my option.

I still live with my old man so he doesn't like a lot of noise. It would be obnoxiously loud if I had the option.

[Coop[580]

Well..... spend money on getting your own place!! U over 18 and out of school? Priorities... then build your car. But trust me when I was young my priorities were cars and girls... hahah.

[Dega Man]

I really think you will be very pleased with the American Racing Headers Quad Axle Back mufflers, they flow with no restrictions on high horsepower engines and have a very quiet deep mellow tone until wide open throttle with very minimal drone. They are not loud with cats deleted.