I am wanting to purchace the megan racing header which as most of you know comes with a straight pipe in place of a cat. Is driving with no cat + header and my aftermarket exhaust going to cause problems with noise, smoke, or anything else? Any advise would do thank you!

 

Yes.
Noise: more
Smoke: no more than now, which should be none
Anything else: well, there's the environment... and the federal law about messing with emission systems to protect the environment... and the check engine light to tell you there's something wrong with the emission system on the car, to protect the environment....

Or not.
I hope this is not a troll.

 

actually, on my old srt you would get a slight rich burning smell without the cat in place...

noise levels definitelly go up, considering how quiet the Alta 2.5" exhaust is already, i might give it a shot without the cat see how much louder it's gonna get...if it's obnoxiously loud, i'll throw on a cat.

Just got my OBX today, she's a beauty...unbelievable how nice a system you can get for such little money.
the flange that goes up against the exhaust side of the head is not 100% flat/true though, it's slightly slightly off in the center when laying it down on a perfectly flat surface...looks like i might need to mill it straight, i'm not sure the gasket provided will fill that space without doing it.

 

yea i love my obx cat-back. It works great, sounds great, and cost 1/3 of the price as many of the others. The only thing about it i didn't like was having to cut my old exhaust and clamp with the cheaper clamps they give you. This created a small exhaust leak but i should be getting it welded to fix that soon.

As much as i want to protect our ozone and keep greenhouse gases low, paying $800 for headers with a cat is out of the question w/ my price range.

Is it possible to run the stock cat with aftermarket headers? If so, will the performance of the header be severly affected?

 

P.S- Where did you purchace your obx headers?

 

on ebay.

tuningdepot i think.

i've been told the stock cat/or any other cat would cut about 3-5 whp vs not having one.

 

Maybe your perfectly flat surface isn't so flat. If you have access to a carpenters framing square lay that edge wise across the flange. Or better yet use a sheet of plate glass lay the header flange on that. Use feeler gauges to measure between the flange and the true flat surface to find the run out/warpage.
Remember, measure twice, cut once has stood the test of time.

 

oh it's definitelly warped a little, you can see it open eye never mind if you lay it on a flat surface.
i'll see if i can take some pics tomorrow for you, see what you think.

 

But if it's a street car, you will earn the scorn and derision from people like me who care about our air. Catless on a street car is a very selfish act.

Matt

 

well, you live in one of the most polluted states, while i live in the cleanest air state, one little Mini won't put that much of a dent in our enviroment.

No need for a feeler gauge, like i said, you can see it clearly...you tell me:





Otherwise, it looks very well made...don't know if that little bit of space can be sealed up proper by the gasket, but i will probably mill a slice off it to be sure.

 

" i will probably mill a slice off it to be sure."

Difinately. The gasket would, most likely, seal but you are way better off with a flat flange.

 

Actually, Atlanta or Denver now has the worst air... No longer LA. But it's thinking just like this that sucks. If everyone thought that way....... Sorry, but every time I see you post that you're going to go catless chasing after a few HP I will point out that you are being a selfish person. Go ahead and do it, but accept the consiquences like an adult. You're choosing to crap on the air because you want things a bit better for you, and don't care about the impact. I think that sucks, and it earns no respect, and opens the door for people calling you out for being the selfish actor that you seem to want to be.

Porsche GT3 come with cats. Z06 corvettes come with cats. The Mercedes Maclearin comes with cats. I guess that they are compatible with power generation for street cars.

FWIW, Performance Peddler (Google them) out of San Diego has the lowest price on magnaflow cats I've found. But the price on the phone is less than advertized on the web site.

And for whoever asked, the stock cat does better than most think, and lots of us OBXers have it welded onto the stub. It seems the Mini cat can take the heat of our boosted rich running engines better than some of the ceramic aftermarket cats....

And why accept a header with a bad flange? Get it exchanged.... Also I think I got mine from SparkTek motors (or something like that on eBay). They do have a real store in SF somewhere..... I was talking to them about picking up the header in person to save shipping.....

Also, the gasket they give is thick soft stuff. I few thousands should be fine (up to .010 or so?). I was surprised how much give the OBX gasket has... One other thing to look at before you bolt it on. Some of the welds can be very close to the holes for the bolts. A little time with a dremel while it's on the bench can save you a lot of cursing when you're bolting it to the car. Also, (though yours looks better than mine) some of the primaries may not come out perpendicular to the flange, and this can prevent you from useing the bolts, I had to use one stud on mine.


Matt

 

WOW this isn't the tree hugger's thread. OK i'm ready to get flamed


P.S. Get off your soap box.

 

this would be another + what ever for installing a cat

The stock cat does a great job.

The local machine shop here would plane that flange for less than the postage, about $10 & it would be perfect. The mounting holes, on the other hand, can be a big pain on this or any other header, for any application ( that's why 12 point header bolts were made, unfortunately not for the Mini ).

 

You don't get to moderate the conversation. I'll call them the way I see them until I'm banned.

Matt

ps, and if you didn't notice, not only did I rag the guy, but I also pointed out ways to save $ on Magnaflow cats, and pointers on how to instal the OBX header based on the experiences of others who've been there. With me, it's a whole package deal. I post tons of help, and I call those out that I think need a bit of a biatch-slap! All or nothing..... You are free to place me on your "ignore" list if you don't like it.

 

i was playing with you Dr.
you don't know me yet, i'm quite the sarcastic fella'...you were too easy, i had to keep you on your toes a little, i might have even given you another gray hair or two, lol...

i'll reuse the stock cat, i can't stand too much exhaust noise, you know, the obnoxious kind.

i'll check around machine shops and see who can shave off that flange.
returning it might take too long, but i'll look into that also.

 

I wasn't trying to moderate the conversation, I was as you put it "calling them the way i see them until i'm banned".

I just think its funny that you make this big deal about not running a cat, I'm sure theres things we could all do to make the air cleaner.

 

Loud has been played.
The stock cat is a very good piece, better than most think.

A shave will make the flange better than new, even perfect new. This is a process I've done for years with all kinds of headers. Even the best can be off.

 

Particularly when the general population count is high. In fact its big enough that states actually create laws against it.

You're correct in that there are other ways to help make the air better, but in the context of this forum and its members, using a CAT is a good place to start.

for Dr.Obnxs for taking the community into consideration.

 

Picked up my OBX after work. Very impressed. I haven't put a straightedge to it, but the flange on mine looks to bow the other way just a little. Ports need a little touch up with the die grinder to match the gasket, then it's off to get ceramic coated.
Thanks for everybody's input!!
Jim

 

Make sure that you dremek around the bolt holes as some of the welds keep the heads of the bolts from going flat. And make sure that the primary is perpendicular, or have a few studs on hand in case you need them. Where are you getting the coating done? Here in the south bay, Replikanisher Machineingsomething are the only guys I found....

Matt

 

Some info about catalytic converters:
http://www.howstuffworks.com/catalytic-converter.htm

http://www.catalyticconverter.org/law/index.htm

http://en.wikipedia.org/wiki/Catalyt...d_deactivation

 

Good idea!
Think I'm going to use all studs. Nissan has some really nice exhaust studs and locking nuts, and since I work there....
I'm going through the same place that TonyB used.
http://www.crucialracing.com/
He acts as a go-between. I'll drop off the header in SF and he takes it to Santa Clara with his other parts and then picks it up and brings it back when finished.
Jim

 

you're talking about using studs instead of bolts to bolt in the header?
who sells them for the Mini?

 

did a little work on the header in the past couple days...

some gasket matching, scribed a line and took the sander to it...



a little deburring on the edges of the welds near the bolt holes



back from the machine shop, got it planed a thousandth or two



nice and flat (never thought i'd ever hear myself say that)