Anyone remove the primary cat?

[guitarguru44]

I've searched and searched and did not see this done yet. There are plenty of people who have removed the secondary cat but I do not know of anyone who has removed the primary cat. This would free up some horsepower and torque and I'm sure the car could be tricked to not throw a CEL. I assume this is done on the supercharger and turbo kits but I can not find any decent pictures for what those exhaust set ups look like. Yes, I know this is bad for the environment, illegal, and might make the exhaust fumes smell bad but I am just wondering if someone has done it or if anyone plans to do it and has a dyno to show results. Basically I don't see why we can't remove this downpipe, cut off the cat, weld on some pipe, seat the O2 sensor further away from the cat, and bolt it back up.

(Also a side note to the moderators: Should I post this in the engine section or post this here in the aftermarket section?)

[Tyrod]

On a street car I think your idea is pretty irresponsible. While no doubt you could pick up some power while doing so, you'd need to tune for it. Today's aftermarket high flow cats only rob a couple of horsepower while still doing their jobs. I'd rather see you go in this direction. Of course, to derive maximun benefit you'd still need to tune.

As for the front O2 sensor. You could just leave it alone. For the rear O2 sensor, just delete and reprogram to not look at it or use an O2 spoofer.

[guitarguru44]

Originally Posted by Tyrod

On a street car I think your idea is pretty irresponsible. While no doubt you could pick up some power while doing so, you'd need to tune for it. Today's aftermarket high flow cats only rob a couple of horsepower while still doing their jobs. I'd rather see you go in this direction. Of course, to derive maximun benefit you'd still need to tune.

As for the front O2 sensor. You could just leave it alone. For the rear O2 sensor, just delete and reprogram to not look at it or use an O2 spoofer.

It is just as irresponsible to remove the primary cat as it is to remove the secondary cat which a lot of people have done on here. But I'm not here to debate that in this thread, I'm just wondering if anyone has done it. For my own car I don't think I would do this being that if your car is pulled over with no cats it could be impounded on the spot and I wouldn't want to risk that.

I would think replacing one of these cats with a high flow cat would probably only allow you to gain half of the hp than if you were to just remove it and run a straight pipe. Also I don't think you would need to tune anything by removing the primary cat.

I guess the reason why I am interested in this is that the secondary cat removal pipe is the best hp gain per dollar (5 hp for $150 = 1 hp/$30 as opposed to an intake 4 hp for $250 = 1 hp/$62.50 or catback exhaust 8 hp for $550 = 1 hp/$68.75) and I think removing the primary cat would yield even more power for less money. This is likely the best hp/$ mod you can make and should be completely safe and not harm your car, but the tradeoff would be it is illegal (like the other cat removal), bad for the environment, and might make the exhaust fumes smell bad.

Additionally I would be curious if anyone knows where the best place to sell back these cats would be. The Honda msrp for the primary cat is $980 and the msrp for the secondary cat is $730. It is likely that you could actually make money by selling both of these parts after you remove them from the car. So essentially you could make money and make your car more powerful.

[guitarguru44]

Kind of surprised that no one has done this on a CR-Z yet.

[northbridge]

actually the secondary cat does MUCH less than the primary when it comes to responsibility, but yeah.

havent done it and i dont think anyone has.

reason being you have to make something that bolts to the flange on the exhaust side of the motor. Closest thing is a part weapon R makes for the FIT but theres no confirmation if it will be a direct bolt on.

also, selling your cat will make you like no money. OEM prices are unobtainable in the real world.

[sgtmorph]

Originally Posted by northbridge

actually the secondary cat does MUCH less than the primary when it comes to responsibility, but yeah.

havent done it and i dont think anyone has.

reason being you have to make something that bolts to the flange on the exhaust side of the motor. Closest thing is a part weapon R makes for the FIT but theres no confirmation if it will be a direct bolt on.

also, selling your cat will make you like no money. OEM prices are unobtainable in the real world.

regarding the weapon-r header......
ive done the research on this a long time ago.
after comparing the new fit's manifold with ours, i'm 99% sure it will fit.
one problem is that it costs over $300 bucks.
but if someone makes it work, you can easily expect to gain about 8 dyno-proven whp.
i did this same header on my civic 2 years ago and i got 8 whp on the dyno.
these integrated exhaust port systems we have respond very well to better breathing ability.

[JDM CRZ]

Any more info on this?

[IsaacMTSU]

I know the cats are pretty pricey, even selling them to a scrap metal place you can make a couple hundred bucks. I saw on the news a while back that people were cutting them off cars instead of stealing the whole car

[sgtmorph]

Originally Posted by JDM CRZ

Any more info on this?

Not until someone comes up with $300 and test fits the weapon R Fit header...

[Old School]

I took the second cat off, but loosing the first one too might be too much. As in too much noise, too much open piping, and too attention getting. Plus our engines are already really low on low end power, doing this would absolutely kill the low end. I honestly do think there will be an over-all gain with that much loss of back pressure.