no body wanna answer this simple Question ?

 

I'm sorry I can't answer as I haven't installed mine yet. Sorry.
Anyone else?
Jim

 

I dont really know what your asking.
-If your asking if you'll get more power by taking out the resonator and welding on a cat.
- no you will lose power, because it is more restrictive. (but it will get quieter)

-Now if you have your cat bolted on and you want to weld it on for more power
- dont bother, you wont even feel a difference.

now because this thread is about OBX (4-2-1) vs. Megan (4-1)
I will start off by explaining the differences.

anyways I will start off by saying, most race cars all use 4-1 headers. If you were to look at any race bikes you will see that they also all use 4-1.

People defend the 4-2-1 design because they base that on the x-pipe vacuum design(I kinda named it myself, if there is a propper name for it excuse me).
you will see this many times on cars with a v8 because they have 2 sets of exhaust ports on opposite sides of the engine. There will be 2 headers that come from both sides of the engine which connects to 2 seperate exaust pipes. The pipes will then cross somewhere in the middle of the car and then at the end have 2 seperate exhaust pipes on the *** of the car. The reason for this is, Lets say the exaust gas from the left side of the engine flows down through the pipe as it passes through the cross section of the pipe it creates vacuum for the other side pulling the exhaust gas for the right port making the flow of the exhaust very efficient.

The reason why it applies to the 4-2-1 is because every time pipe connects to another, in theory it should apply vacuum to the other exhaust ports. And obviously the 4-2-1 has more connections to create vacuum than the 4-1. A single puff of gas blows by 2 connections in a 4-2-1 as opposed to just one connection on a 4-1.

But (a proper) 4-1 works in a completely different manner. It was not created to make vacuum. Its more created to make the gas spin through the exhaust pipe. An order for this to happen though, the runners into the collector of the header have to be postioned according to the firing order of the engine. As the exhaust gasses expells from the runner into the collector the exaust gasses expand pushing the exhaust gas before it into a a spiral motion. This in turn is the most efficient way to expell liquid or gas from a narrow space.

you can test it out yourself.
Fill up a bottle with water and try everyway possible to expell the water out of the bottle and time it with a stop watch (squeezing is cheating). you can flip it straight upsidedown, let it drain at a 45 degree angle, shake it vertically while upsidedown, or swirl the water inside and then drain it out.

--well I definately explained that like a retard. Its hard to put it into words.

But bottom line is the 4-2-1 is created for street drivers who want more low-mid range torque. This is because with the design of the header it ended up not being as efficient as expected because of the loss in propulsion due to connecting to 2 pipes. This inefficiency became marketable though because it was easier to drive due to the low end torque, yet more efficient than what vehicles come with stock.

4-1 is still being used with most forms of racing, this is because most race cars are always driving in the top end of their torque curve. Also 4-1 ends up pulling out more peak power out of the engine.

I have a 4-1 in my car. I swear by them.

But then again it all gets ruined by the r53's gay exhaust design. That is why i will be running with the Altas single pipe exhaust. If you understand my explaination for the 4-1 you will understand why I will go with this route.

Also keep in mind that the mcs has a supercharger so backpressure hinders much more than helps. N/A cars a different.

Sorry for the lousy explaination. This is the best I can do. But now Im also too tired to reread. I will edit any misunderstandings tommorrow.

 

Hello guys!

I was wondering if anyone ran into this problem with the Megan headers. My 02 sensor that are on the headers is so close to the heat shield that I cannot plug my 02 sensor in. What can I do? Is it bad to run my car without it and only the 02 sensor on the cat?

-Paul

 

You have to run the 1st o2 sensor. That is a major sensor reading for the DME to make the engine run as it should. The 2nd o2 sensor does not do anything other than monitor the cat you no longer have. Looking at the header you clearly already ran it without it. I have no experience with that header but you need to go to an exhaust shop and have the o2 sensor bung moved.

 

I ran the car for about 10 blocks. So, I took the shield off, and it fits now, but I don't have a long enough 02 sensor since the sensor is placed way lower than the original place. Is is possible to buy a longer one? I just need a little more length. Also, is it bad to drive it a little bit? No freeway, just little city blocks.

 

https://www.google.com/search?source....0.GwsXAbGOpDM is this what you're looking for?

 

Thanks for the help, but I cant find one that says it is clearly for a Mini Cooper. I was going to look at other one that seem to fit it, but I didn't want to order it online and get disappointed that it doesn't fit. If you know one that fits, that would be great if you can send a link. Thanks again for helping out everyone!

*Update*
I actually got the o2 sensor to fit! I had to take the o2 sensor harness off the socket and pull it closer towards the bung. There is a little pressure near the o2 harness because I had to bend it towards the bung, but it should be fine. There is still a little slack. It is not pulling against each other. What do you guys think?

 

The extension you would need is not a proprietary piece. It just needs to be for a Bosch O2.
If what you have now is working and you are satisfied with the slack available in the harness, you're good to go!

 

As of right now, it is fine since I rarely drive it, but I would want to buy a extension if I know what im looking for. Can you send me a direct link to the product and do you know if I can buy it at any auto parts store? Is it something like this? http://www.ebay.com/itm/O2-OXYGEN-SENSOR-EXTENSION-12-LT1-CORVETTE-4-PIN-FLAT-/290621373069?pt=Motors_Car_Truck_Parts_Accessories&hash=item43aa623a8d&vxp=mtr
Do you guys think that a o2 angle adapter is reliable because I think that would help me clear out space near the heat shield too?

 

I am also looking for this. Did you ever find one?

 

I've just fitted OBX headers to my 06 R53.
I was running OEM headers with a 2 1/4 Quicksilver cat back system with one muffler which had a very loud bark and would bang and pop quite badly. To ease the harshness I fitted a mild steel 2" resonator just after the cat which took some of the bite of the exhaust note and didn't restrict flow too badly.

Since then I fitted the OBX header, a hi flow cat with 100 cells per square inch and replaced the 2" resonator with a stainless 2 1/4". I fitted the hi flow resonator because I couldn't see the point in upgrading the exhaust system to only re-fit the restrictive OEM cat. There is a huge difference when you compare the cores of the 2.

With the header, cat and bigger resonator the exhaust is okay up to 3500rpm and then it becomes rediculously loud! Also, unless you accelerate very easily the exhaust bangs and pops very loudly between gear changes.

Even with the new cat I had an issue with the post cat CEL coming on. I reset it but if I accelerated a little heavily while the engine was warming up it would trip the light. I ended up getting a 90 degree adaptor for the post cat O2 sensor which fixed the CEL issue. Before fitting the adaptor, the engine was also running rich.

It's still very loud so I'm about to add a Magnaflow muffler and hopefully that will fix the volume issue and give it a nice exhaust note.

I was surprised at how much louder the OBX is over the OEM header!!