Hi,

I'm confused about couple things. I have read some threats about exhaust and backpressure but couldn't come to a conclusion.

I have just purschased the OBX header for my MCS.

Here is my questions:

What happens if OBX - DECAT - Straigth pipe with a small silencer?

What happens if OBX - Stock Cat - Stock exhaust?

What happens if OBX - DECAT - Stock exhaust?

As you can see, I don't have any money left for a decent exhaust system (Coilovers are expensive)

 

Just run OBX and stock cat stock exhaust

 

It looks like OBX offers hi flow cats for certain vehicles like the civic, etc. or at least the same seller does for the one on ebay:

Header:
http://cgi.ebay.com/ebaymotors/ws/eB...RK%3AMEWA%3AIT

Cat:
http://cgi.ebay.com/ebaymotors/ws/eB..._BIN_Stores_IT

What does everyone think about the cat? Better to use stock? Does the stock cat restrict THAT much? I would do the MTH header and file, but if I can save the money from that I can buy an exhaust for free with the header and tuning file. Plus, the OBX is a 4-2-1 header, unlike the MTH. Although the quality of the MTH is obviously superior. I just want to know what my options are here. By the way I drive a 2005 COOPER, not an "S".

Any help is appreciated!

 

I've got mine set up with a Magnaflow "high flow" cat. I say that in quotes because I was told that it really isnt a high flow cat, although the box says so. Anyways, truth be told I keep throwing CEL's even after clearing them a few times. So I'm going back to the stock cat and see what happens. Its definatly smaller than the Magnaflow, but maybe will make the difference.

 

How much was the magnaflow?

I think it may just be worth it to do the MTH package since the combo is known to work together. You're paying to avoid problems which is money well spent.
I have enough problems to deal with !

However, Because the reg cooper doesn't benefit from the decreased backpressure the same as a forced induction car does, maybe I should keep the whole stock system from the MTH header and cat back. Then later I can add just a muffler if the mood strikes. It would be pretty sleeper with the stock exhaust at 140+ bhp.

 

These are " cat delete " units and shoud be advertised as such.There is a kit that fools the el light into thinking everything is ok but what if you get pulled over and get emission audit.I know around here they dont take kindly to cat delete or no cat bypass.

 

I want to have an operating cat because it reduces harmful emissions and I like to be green.

Are you referring to the Magnaflow unit? Because the MTH header has a cat on it that is as good as the OEM unit. This allow for the oxygen sensors to operate on the correct "closed loop" and not fool the sersors and throw codes. Here is the MTH unit:

https://www.mth-usa.com/sess/utn;jse...dex.shopscript

Can the OBX header and a good cat be hooked up to the stock exhaust system? How about the MTH header and at with the stock system? Sure would be a sleeper with 140+ bhp on the stock exhaust!


Comments welcome!

-Steve

 

Well that Magnaflow cat was $135.00 and I'd let it go for a reasonable price. I might have 300 miles on it. I just clamped it in instead of welding so I can take it out. I've got the box and the CARB certificate still. It defenatly flows better than the stock cat. Its a bit bigger being oval, 2.5" pipe and a tad longer. It kept throwing a code that said I was running lean, which is contrary to what I had before w/o any other mods -rich as a pig.

 

A lean code is from the front O2 sensor, and isn't effected by the cat. If the secondary O2 shows faults, it will be cat efficiency. The lean condition can be from the header flowing more efficiently, and without an ECU retune, the car just isn't squirting enough gas at light throttle (probably on the freeway at constant speed).

Right now I'm running the OBX, stock cat, and one-ball. I did make a custome single sided exhaust, and it cooked the cat due to lean tune before I got my MTH adjusted (but don't worry, I did a larger TB, the header, magnaflow cat, 2.5" all the way out and free flow Supersprint muffler). It could wake the dead, and it wasn't the parts that gave me problems, it was the tune not being matched to the parts. there are lots that of people that run the header without a tune package and are fine. The farther you go from stock, the more likely you are to get codes.

Matt

 

I started w/ obx header, stock cat and 1-ball and I thought it was a great set-up.

I subsequently, decided to try the OBX exhaust (299) because I was so pleased with the header. I felt I got alot of exhaust system for header (200) + cat back (299) = 499 when that doesn't get you a cat back from many manufactures.

But back to the point even if you are low on dollars, you can still have a GOOD system = obx header + stock cat + 1-ball. I have no figures to back it but I bet this combo beats many aftermarket just catback systems.

 

Dr. O: thanks, that makes sense. I was wating to do the MTH, why I dont know but now I know I have to.

 

Hi,

Can you recommend a place to do the one-ball in Miami? I don't trust anyone down here! Too bad it requires welding, or I'd attempt it myself.
Did you bring in the pipe when you had it done, or did the shop create it?

Thanks!

 

How do you know? Have you had both to compare? What kind of testing have you done? Do you Have and data to back up your claim?? -- Johan

 

The Magnaflow had more flow, but it's build left something to be desired. The MTH header has more flow on paper, but I don't have any data to show it. I never bought it. I cooked the magnaflow, but I'll be going back sometime. More flow capacity, and dual bungs for my wideband.

Matt

 

Absolutely, MyMini in pompano beach has the part and right next door is Redline. Peter from mymini can coordinate eveything for you. to hook up with peter get his number from www.myminiparts.com

tell him I said hi. he's done all my work - worth the trip, great guy good conversation.