Hey guys I am about to install my obx headers. What power gains do you think i would ain by removing the cat? Is it worth it? Also will to O2 sensor get bad readings and put the check engine light on? Thanks for all your help.

Sami

 

I think the benefits to Cat out wiegh lossing the Cat.

 

I concur with Bahamabart - read Randy Webb's FAQ about why a cat is a good thing for the Mini at the bottom of this page:
http://store.webbmotorsports.com/ind...in_page=page_3

When I installed the OBX header with the stock cat, I saw some impressive gains - more than I expected, anyhow. I doubt that going catless or with an aftermarket cat would help improve performance significantly, since the Mini already has a pretty nice OEM cat.

Whichever way you go, good luck with the install, and let us know how you enjoy the OBX!

 

What we need is a good after market cat that dont cost 1000.00 that is bolt on,then you could use an inexpensive header without having to cut and weld everything.

 

No cat = better performance. If the cat was good for performance then all racing Minis would re-install them.

I drove the later part of last tracking season without a cat and would never go back, but I'm not street driving this car anymore.

 

Onasled has a pure track car. If you want to reduce the back pressure, get a larger capacity cat. The loss of the pre-cat, adding the header, and a high flow cat will do a lot for your car. If you go with a cat-back exhaust, it can get VERY LOUD, so be carefull what you put on.

I bough a Magnaflow cat (with two bungs so that I could run a wide band) for a bit over $60 shipped to my door. The thread is here.

Personally, I think getting rid of a cat on a street car is a very selfish, irresponsible act.

Matt

 

No cat. I'm putting a Suspersprint setup on my car. SS header, midpipe w/o resonator and exhaust w/center out (I have a Cooper). If you go catless, you will still have a bung for the primary O2 sensor in the header but will have to tie the secondary one up because the secondary is after the cat. Either way, if you go catless, you will trip the check engine light. But to some...that's not a big deal. When it comes time for emissions, I am going to put my OEM unit back on. Like the previous post said....If somone can find a high-flow cat that bolts up and doesn't cost a grand....I'm in!

 

Please don't take this wrong, but....what kind of gain [and at what cost to the environment] do you anticipate in ex-ing the cat on a _cooper_? You're gonna lose back pressure, lose low end torque, and put out far less refined exhaust. Plus, it's gonna be really really loud...

I'm agreed 100% with Dr. O... this isn't just about personal choice...

 

DR Obnxs:
Which Magnaflow cat did you buy(part no???)? Did it throw any codes? I have to replace a cat on a 421 style header and would like to get the one with 2 bung holes .

 

No codes. Rated to 6.2 liter displacement.

Matt

 

What was the price.Did the flange bolt up or was it modified?

 

and it says $84 each, 2.5" in/out and it has to be welded. When I called in person less than a year ago, I got it shipped to my door for $60.
You can always sorce flanges to get welded on and make it a bolt on.

Matt

 

I don't run a cat and don't ever plan on going back to one. Sure the check engine light comes on, but you don't have to worry because if something really bad happens it will flash.

If the exhaust is too loud just install another resonator or buy some ear plugs (I keep a set in my car for my girlfriend ).

I can't understand why you would buy an aftermarket header and then block it off with a cat.

All that being said the exhaust system on a MINI isn't going to do much with the tiny exhaust ports on the heads that come with our cars. If any of you have seen them you know what I mean.

 

This is quite true. Which begs the question, how can one expect much improvement unless the car is a) running nitrous [like you], b) turbo'ed, c) running a ported head, or d) running at least a smaller SC pulley? In a Cooper [!!] or even a regular S, you're not gaining anything noticeable, from everything I've heard from actual users. It's silly, imo.

My stance on power: 5 peak horsepower is not noticeable. 5 down low is _slightly_ noticeable. But, lose the cat and lose back pressure and possibly lose torque, especially N/A'ed...

 

Catalytic converters are on cars for a reason, and it's not to restrict power .
Combustion produces many products like carbon monoxide and nitrogen oxides that ARE HARMFUL TO THE ENVIRONMENT. If this was some SUV enthusiast site I wouldn't expect people to pay attention, but it is not and I believe everyone here, in some capacity, took the environmental impact of their vehicle choice into account while purchasing it.

Check out this quick rundown:

http://www.lcc.ukf.net/kskills/catconv.htm

If you are not running your car as a daily driver, like onasled is, then removing the cat may be something to consider, or at least replacing it with a highflow cat, like the one used on the MTH header: https://www.mth-usa.com/sess/utn;jse...dex.shopscript

It is your RESPONSIBILITY.


Good luck,

-Steve



edit: merry xmas!

 

OBX header, cat in or cat out,either way it won't improve your proformance much.

 

that's just sad and dissapointing.

Matt

 

I've owned cars in the past that I de-cat'd. In retrospect, it was irresponsible regarding the environment for just being a street car. ...but that's not the real reason I won't have a street car w/out a cat anymore; when I get out a de-cat'd car, I STINK like pollution. It's totally not professional for me to show up at the office smelling like a tailpipe. So my two cents for all you street-drivers, the 1HP you'll gain from de-catting your car will be the smelliest 1HP ever.

 

I apologize for dissapointing you but that wasn't exactly what I was going for. I am however satisfied with my exhaust note and the "performance" of my exhaust. If that costs me some brownie points with a few people... Well it's no loss to me.

All I was doing in my post was stating what I felt was the best way to go, at least for me. And I gave a few facts as to why I feel that way. I certainly don't appreciate the disrespect.

 

One must ask where the disrespect lies: to different people, in different places. Respect of each other, the law, etc...we choose.

 

But respect is earned, not demanded. Taking the easy way out based on your desire with no regard to the effect on the environment in a street car doesn't earn it from me. Look, the high end porsches come with cats, the latest Z06 corvette comes with em to. So with proper selection, you can have a cat that cleans the exhaust and provides the performance level you want. You just chose not to, and accepted the fact that your decision would have impact on others, and chose to do it anyway. In what way does that course of action require me to agree with or give respect to your chosen course of action? I wasn't rude, but respect. Sorry, you didn't earn it from where I sit.

Sorry if you don't like it, I don't mean to be insulting, but I can't sign on, when for less than $100 in parts and the same in labor, you can have both the performance (or close to it) and the benefits of reduced CO and unburned hydrocarbons.

I'll stick with what I said. I am both saddend and dissapointed that there are those that choose your path with street cars.

Matt

 

I'm not judging anyone, but it is each driver's responsibility.