Long Tube Headers with High Flow Cats

[BCeagle08]

What about long tubes with normal cats welded in? Would the long tubes alone make any change to tone over stock?

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[Grimace427]

What about long tubes with normal cats welded in? Would the long tubes alone make any change to tone over stock?

Stock cats are huge in comparison to the race cats that come with longtube headers. They fit in a stock car because of how small the stock headers are compared to longtubes. Adding stock cats to longtube headers would not fit very well, probably scrape a lot on speed bumps. Plus the difference in collector diameters would make that a not too great idea.

 

[BCeagle08]

Gotcha, thanks

 

[Joe 5.0]

Kooks states their Green Cats pass emissions readiness tests with the scan tools, not a visual inspection. So, a tune is not required with the Kooks Green Cats so when the emissions test center plugs in their tool to the OBD2 port, you won't have any non-functioning sensors or failed readiness tests when performed. They say on Ford vehicles, it was something like 90% of cars successfully pass emissions with the OEM calibration.

To answer the OP's original question, yes, the note of the exhaust will still change but these high flow cats STILL release a lot of volume. They do help tame some of the sharpness of a non-catted system, but don't expect the volume to be anything like stock manifolds and cats with a resonator delete.

You could do the Kooks Green Cat long tubes that connect to the stock resonator, leave the stock resonator and then use an axle-back of your choice? Let us know if you have any questions about ordering a set-up like this.

Thanks.

So I can install Kooks LT headers with green cats and NOT have to tune my GT?

 

[beefcake]

the cats will quiet it down just a little bit, but not a bunch

 

[Texican1911]

I installed S&W long tubes

Smith & Wesson?! :cheers:

 

[smokinzx14r]

Smith & Wesson?! :cheers:

Yup :lol:

 

[arcadewilco]

I have the Kooks Green Catted with the Ford Racing Touring. It's very loud and awesome on the cold start. However, its quiet on the freeway with little to no drone. Around the street you can hear them but they are not obnoxious. I'll try to post a video soon. This week is Christmas for my Mustang so my build should be complete (for now).

 

[Dragster]

Kooks states their Green Cats pass emissions readiness tests with the scan tools, not a visual inspection. So, a tune is not required with the Kooks Green Cats so when the emissions test center plugs in their tool to the OBD2 port, you won't have any non-functioning sensors or failed readiness tests when performed. They say on Ford vehicles, it was something like 90% of cars successfully pass emissions with the OEM calibration.

To answer the OP's original question, yes, the note of the exhaust will still change but these high flow cats STILL release a lot of volume. They do help tame some of the sharpness of a non-catted system, but don't expect the volume to be anything like stock manifolds and cats with a resonator delete.

You could do the Kooks Green Cat long tubes that connect to the stock resonator, leave the stock resonator and then use an axle-back of your choice? Let us know if you have any questions about ordering a set-up like this.

Thanks.

I was under the impression that catted headers would pass inspection regardless, so thanks for the info. Is there any difference between their "standard" catted headers and the "green" ones in terms of passing emissions? I have been considering Kooks catted headers, but I don't want to deal with failing inspections and all of that...

 

[beefcake]

depends on if it's visual or plug in like was mentioned

 

[Dragster]

depends on if it's visual or plug in like was mentioned

Why will they not pass a visual inspection? Are you not allowed to have aftermarket cats?

Some of these laws are absolutely asinine...

 

[stage3s4]

In NYS you will have issues with some aftermaket cats setting readiness mode and triggering o2 CELs. I guess these kooks green headers are the exception. Maybe others will not have an issue but Its probably more of a guessing game.

I'm assuming you can remove the o2s with a tune yes? I have done this before on other cars and I can pass NYS inspection no problem with catless exhaust setups. I also have used the o2 sensor spaces found on ebay and amazon. They work about 75% of the time.

The main reason I would want to get catted is not sound or passing inspection but rather the smell from a catless exhaust. Do most of these catted headers help with the smell? Also is there any noticeable power differences from catted vs non catted? I have had nothing but turbo cars so I usually never bother with catted exhaust systems. Just don't want to deal with the smell.

 

[Anthony 05 GT]

The problem with longtube headers and any cats is the fact that the cats are pushed back further away from the engine causing the sensors to not heat up as fast as the system needs them to. Some trick tuning can get you to system readiness, but it takes a while.

On the other situation of being to loud or obnoxious I would suggest welding in a set of resonators even further back on the system. I did this on my '05 and it toned things down quite a bit.

 

[krahooligan]

So I can install Kooks LT headers with green cats and NOT have to tune my GT?

THIS. can someone answer?

 

[stage3s4]

The problem with longtube headers and any cats is the fact that the cats are pushed back further away from the engine causing the sensors to not heat up as fast as the system needs them to. Some trick tuning can get you to system readiness, but it takes a while.

On the other situation of being to loud or obnoxious I would suggest welding in a set of resonators even further back on the system. I did this on my '05 and it toned things down quite a bit.

Its usualy not the sensors since they have heating elments built in. Its that the cats do not get hot enough to remove enough NOX from the exhaust stream to give the o2 sensor A proper reading . Cats only work if they get to a certain temperature. Usually the EGTs leaving the cat are higher than the egts going in. Lower temps on the outlet usually means the cat is not working properly. You are right that often times the cats are to far away from the engine and dont get hot enough.

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