Why yall always gotta jump on everyones d*ck about the headers thing? Okay we get it we know there's only one. You don't always have to b!tch about it so you can feel smart. And of course a miata might not benefit from it since its a small motor that isn't boosted and needs the back pressure. but when your trying to relieve back pressure which I assume is why most of us change out our cat back and manifold, dumping the cat is just another way to do that

 

Two words explain why I haven't gone turbo... "SMOG check". I live in Cali & the bi-annual smog checks here suck & limit what I can do legally. We won't discuss what can be done illegally...

Didn't go 2.0L partially because it requires much more modding to the block to relocate the crank trigger & there have been issues with that. Originally I wanted to, but figured it wasn't worth the extra hassle. It's been enough of a pain reverse engineering the ECU to make the car run properly with all these mods!

 

Really not worth the hassle for a couple extra ponies. Near enough the same to not make a noticeable difference. I'll brake 5ft later into the corners and go through 1MPH faster & I can gain more time than I would from removing the CAT.

Now that my aftermarket cat is one the way out (it died from street running before I ever went back to the track, so what does that tell you), ideally I want to import one of the higher grade metal cats that will stay clean longer & flow properly & be done with it. They do exist, but are generally not the ones you see advertised by most companies here in USA.

 

Same place, it's just sitting higher right now and it's being held in place with straps (the one you crank to tighten, whatever they're called in english ).

 

Just to set the record straight, here's what Random Technology says about overly rich mixtures in a cat:
"Fuel, oil and antifreeze cause a different type of brick destruction. Under normal operating conditions, the catalytic process doesn’t begin until temperatures inside a converter reach 500 to 600 degrees (F). If air/fuel ratio is on target, and the exhaust is free of contaminants, internal converter temperature stays at about 1200 degrees. But when unburned fuel enters the picture, temperatures can reach 2200 degrees and either burn the precious metals out of the washcoat, or literally cause a melt down of the bricks. Extremely high temperatures can also result in destruction of the mat that's wedged between the bricks to the converter case."\

 

This is what i plan on doing with a milltek resonated exhaust and milltek header. Do you still get the pops and bangs? If so are they louder/more frequent?

 

Do you have any drone with the high flow cat? or is it just loud when you step on it at high revs. I want resonated milltek with that setup.

 

Been a few years since this thread saw any life. With some companies no longer in business and new companies popping up, what is being installed on headers these days?

 

I recently did Jan's cam, injectors and header/high flow cat package. Absolutely no drone. Headers/cat surprisingly low noise.

Regards,
Jerry

 

Jan's Shorty Header and the Milltek are the top line units. With allot of folks now buying used Gen1s there may be some new interest. The Asian headers are cheap and although there will be those that say they are crap, there will always be somebody out there that will buy one.

On the cats, the rule is thumb is the cheaper the price, the less precious metals to act as catalyst agents and that many will not hold up under the forced induction heat/pressures that the S produces. The other issue is the space where the cat can be installed. The factory cat is about 5.25 inches. There are allot of high flow cats out there but longevity can be linked to the overall diameter and a number thrown around is 130 mm (5.1") but most of the "green" highflows are 6" in diameter so unless they are very short they will be hitting the heat shield on the back end of the unit.

 

It is good to hear that Jan's header (why does that sound dirty?) is not too loud (yeah that sounds dirty) as that is the one that I a looking at getting.

 

Just curious: Is there anyone out there seriously tracking their car with a cat that has lasted?...and I don't mean for one or two days on track...I mean consistently.

 

Kooks is in NC and makes a green cat that they say is rated for 900 hp and the high temps of a forced induction car. Its not cheap and is the "magic" 130 mm in diameter but at 12" long it may top out towards the back. I am thinking the tunnel tapers down about 4" in front of the cat back exhaust flange that coincides with where the factory cat stops. Thinking it is a 300 cell unit.

 

Thx for the lead. I sent them an inquiry and see where it goes. Will post info. if promising.

 

You can call them and talk to the staff, it is their 90142 but do not trust some of the pictures you see as it is 12" long, it is not a slip connection but rather a weld. They have a cheaper unit but he said it would not handle a supercharged system.

Something less in cost then the Kooks green cat is a Pypes CVM11k that is made for a Mustang that they say is rated for forced induction, the problem is they do not sell a single 2.5" cat but rather it is double as the Mustang has two pipes. I have had some discussions with them and told them their cat looks promising as the size would appear to work quite well for an OBX type header. I did not get into the metallic matrix folding with them (see below).

It appears that the metallic matrix holds up better with the higher egt's of our superchargers. Just as the 130 mm diameter appears to be important the manner in which the metallic matrix is folded/wrapped also makes a difference. The simple paper towel type wrap (start in the center and wrap outwards) is the least expensive with an "S" type fold being better. Yonaka uses the "S" wrap but is an inexpensive high flow cat.

This is why I woke this thread up as these types of discussions and manufactures did not appear to have even existed back in the hayday of Gen1 tuning.

 

our headers come ceramic coated now with the Vibrant GESI high flow cat, these are the only ones we have used that have stood up over time

 

Most women will never understand. Here I am drooling and ogling a RMW Shorty Header.

 

Since all states are a little different - do you know if this will pass emissions tests in Oregon? And how much extra is the luscious ceramic coating?

 

Thinking Jan's cat is a CARB unit.

 

Thanks for reviving.

I cut the OEM cat out of a junkyard header and have been using that connected to my OBX ebay header for 4 years now with pulley, big valve head, and ported intake, etc. Zero issues other than routine donut gasket replacement (RTV sealant really helped there).

I switched over to a better long-tube header and have been struggling to find a decent CAT. As much as love the roaring sound of a straight pipe, the smell is terrible and... you know, mother earth.

I'll look into Vibrant. Any other recommendations are welcome.

 

Does anybody have experience with the Vibrant or G-Sport high-flow cats? My stock cat broke in half, so it’s not useable and I cannot find the OEM cat à la carte on the net. I have the Megan header but do not want to run catless and want to eliminate the codes. My r53 is running lean right now.

 

I have had the Vibrant GESI cat and a Mini Madness header for a few years now. It's excellent. Never a CEL.

I have an OBX header with the stock cat welded in if you are interested. Would sell for real cheap.

 

I’d be interested if I didn’t already have the Megan header. Plus I’m really digging the idea of having the GESI on my Coop. Would you say that there is any MPG loss or gain from it? The cat is the most restrictive element of the exhaust, so I imagine the GESI would free up some HP and MPG.

 

I frankly have no idea on mpg. I have a thumper head, cam and everything is ported and polished and I stopped tracking mpg a long while ago. Butt Dyno says there were obvious gains but that was probably mostly from the change to a long piped header which I did at the same time as the cat, similar to your Megan header I believe. I never had the madness header and the stock cat together. I did run the madness header catless for a season and I didnt notice reduced power now that I have the gesi cat so I suppose that is worth something.

I did notice a trememdess reduction is noise and obviously smell (catless was dumb). The shop that installed my gesi cat said they are tough and highly recommended. I have lots of power mods and drive my mini hard and no problems.

 

interested

could you pm or text me price? 8132402904