Ok, Going down from header, I have a o2 sensor and then flex pipe and then it bends under the car and runs into a cylinder about 4 inches in diameter and its about 6 to 8 inches long. I'm figuring this is my converter. This is where my exhaust leak is (Bad) My question is... Will it hurt to cut this off and strait pipe it. Thanks to all opinions. Also my car has several mods and the whole exhaust system is aftermarket.

 

thats your catalytic converter, straight pipe wouldnt be your best answer although its physically possible. you'll get an emissions code and undo the work of a million hybrids. you would be better off getting a replacement cat or get a new header/highflow cat

 

+1^ - Unfortunatly though, if those million "Hybrids" are equipped with nickle metal hydride battery packs....they are acutally hurting the environment.....

If you should decide to discect the manifold, and unless you plan on holding your breath for a long time. You have to wear a REALLY GOOD filtered mask so you don't breathe in any of those harmful deposits in the cat. Some really bad stuff in there.

If the MINI manifold is too expensive. Try the aftermarket ones which run about $500 I think. I have heard some of our club members going that route and having no issues. Just use new OEM gaskets. You will be glad you did.

 

That might create a CATastrophe kind sir...

I wouldn't recommend it unless you are aiming for a pure track car, and are willing to handle any side effects arising from losing the O2 sensor feedback loops to the ECU.

It can (and has) been done in that latter context though.

Happy 4th,

Charlie

 

In removing the main cat the negatives are that you are no longer legal, and that you will just have to deal with the light on the dash being on all the time. You will get better gas milage, by a tiny bit, and the car will perform a bit better. The ECU alters nothing if the post cat O2 sensor is missing. It only uses the precat O2 sensor. Do note though that you still have a pre-cat in that header

 

Hey wise brother -- absent the downstream O2 sensor (post CAT) what does the ECU do aside from throw a CEL? I tend to think that absence of any signal would tend to put the map in a defensive mode.

For example, not knowing the O2 content pre-CAT would in my view justify working toward the rich side of the MAP to ensure that an inappropriately lean mixture wouldn't burn the valves.

If such fail-safe decisions are incorporated in the ECU software, then I can also imagine that the injector timing could wind up less than optimal, unless the program pushes the knock sensor as the final arbiter of AF ratios, which I hope is not the case.

Just speculation - which is not done in polite company I suppose.

Cheers,

Charlie

 

No, not on the R50-53 at least. The ECU tune could care less what's doing with the post cat O2. Just an emissions thing.

 

So onasled, What you are saying is it won't hurt to cut this one off? Also will it throw a CEL on? It's past the 1st o2 sensor and before the 2nd one. I figured it would be far enough from them to not cause that (CEL) problem. Also for the arguments, Here in Ky. it's illegal for a exhaust business to cut a cat off but if a car comes in without a cat on it they can legally put a piece of pipe where it was. Also they don't check emissions here.

 

Just my observations, I gutted out my pre-cat and re-welded where the stock header had snapped along the original weld and reinstalled my header. No CEL's, no leaks, better sound.

 

Not to hijack but in what way is it different/better? I'm thinking of getting rid of my precat. Just a note, I have the jcw exhaust without the resonator. I love the sound as is but deeper/louder would not be a bad thing at all. I just don't want it sounding tinny.

Thanks.

 

It's just a tad bit louder than stock. To me, it sounds a little more bassy than before. I realized it more today when my wife drove and I was outside while she took off. I have also noticed that my exhaust tips do not have as much soot after driving. They are way cleaner after I did my little surgery.

 

Thanks. It's not too droney is it?

I'm torn between removing pre-cat from stock manifold or getting a header like the OBX. I'm sure there is more performance to be had from a header and probably better sound, though that is subjective, but a little more costly.

I'm surprised your tailpipes are cleaner...You'd think the cats would collect that crud rather than letting it pass through...Who woulda thought!

 

Nope. Not droney at all. I use her right now as a daily driver and inside it sounds sweet. I am going for the aftermarket header in a few months. Since my weld broke, I figured I might as well try out how it would be without the pre-cat.

 

Sound clip anyone? I'm debating doing this...or just getting a full exhaust...answer is quite obvious..

 

If you can afford the header then get that.

I rocked the one-ball for a while but a full exhaust is miles better. You just get a deeper sound and more volume. While I could kinda hear the one-ball from the cabin, once the JCW went on (sans mid silencer) I can really hear the exhaust now and it's awesome.

Don't delay any longer!

 

On a side note. You may want to check with dealer. Nissan fixed a leak I had at that point on my Altima free of charge, well outside the warrantee, service guy said federal law means they have to fix that area for like 10 years.

May be worth a check.