So I'm looking to do a header and a high flow cat and need some advice cause i hear some set ups cause a CEL. Doesn't anyone have a Header/High Flow cat they can recommend. I want to avoid welding a factory cat onto a aftermarket header. I'm looking for something i can bolt on and not have to worry about since at some point I'm going to have to go through emissions.

Thanks in advance.

 

I have the RMW shorty header.

Jan welds a high flow Random Technologies cats to his headers. I've had it for 10 months & no CELs but it's a lot louder when you floor it (W/JCW exhaust).

 

The MINI runs some awfully high temps thru the cat. The OEM one has consistently been the best performing one.

RMW has had problems with those cats also.

 

Mynes V2 with fabricated OEM cat. excellent setup and NO CEL's

 

I've looked into a header and done nothing yet because people seem to have CEL issues with them for no rhyme or reason

 

+1

https://www.northamericanmotoring.co...pierience.html

 

+2

The RMW shorty also likes to crack around the flanges, thats what happens when you omly weld the outside.

 

What about the OBX or Megan headers? I know CEL is still a potential issue too.

Is doing a header replacement just not worth it when you change the exhaust out?

 

The OBX & Megans are just fine, 99% of the time CEL's are CAT related when it comes to headers, if you went back and read my thread I stricktly chose the Mynes header for ease of maintenance, because of the heat, you WILL eventually end up with a CAT issue when useing a header, and I would rather be able to unbolt a CAT than pull a header, and yes so far the factory CAT's have been holding up the longest. So IMO I would chose a design that uses a bolt on CAT.

As far as RMW's shorty and the Mynes V2 being mentioned so prevelently, they both have the reputation of being the prefered choices as far as performance goes, esp. with more heavily moded cars, but any of them will give you a bump in performance & sound depending on what you're after.

 

I have the Milltek header with hi-flow cat and have not experienced any problems. Installed in April 2003.

Kevin

 

I had RMW's race header and high flow cat with on problems until I had to have it smoged (Calif). How I have the same header with the stock cat and I like it better and it passed smog in good shape. The sound got deeper and I haven't any power loss because of the cat.

 

I have been running an Alta header w/hi-flow cat and an Invidia catback exhaust system on my R53 for the last 2 years and have been very happy with the sound and performance... I have been getting an intermittent CEL light for the last couple weeks and when I took the car in for annual inspection the code popped up that I have a bad CAT...

I would like to just replace the CAT, but have no idea of aftermarket alternatives. I know the the header will have to be removed, the old CAT cut out and a new one welded in place, then reinstalled...

What are my options at this point?

Can anyone recommend a replacement CAT?

 

Does the cooper, S, and JCW all use the same cat? Or is the JCW better than the base model?

 

All the same

 

Go with the stock cat. Just read the previous posts about the problems with the aftermarket cat's.

 

I appreciate the response, but hardly helpful seeing that the OD of the pipe in/out of the stock CAT is much smaller than the ID of the Alta header I am using. Even if an adapter flange were fabricated to make it fit, performance would suffer from the step-down in pipe size to use the stock CAT.

I want to replace the CAT on my existing Alta header. Any info on a suitable replacement CAT would be appreciated.

 

Look up Random Technologies, they are the supplier for multiple aftermarket companies. If they can make a cat that will hold up on a 1000 HP turbo street car a 200 HP MINI isnt a problem. You need a 2.5" inner diameter with your header.

 

Or why not just delete it?
Good luck as you will need it..........lol

 

Thanks for the info... I've checked out the Random Tech CATs from the reference earlier in the thread and the look good... I just need to match dimensions when I get the old one out...

 

Why is there always a smart **** on every forum?

 

Personally would go with the RMW street header. There were some CEL issues when they first came out, mine had one shortly after buying one of the first batches, but Jan sorted it out and it's been code free for almost 4 years! As far as I know, RMW is the ONLY company that actually fixed their header so as to be code free.

 

Maybe I'm missing it, but RMW doesn't list a street header on their website... The only headers listed are not for street use...

Even so, a new header / cat combo is going to run $800 - $1400... The price of cutting out the old CAT and welding in a new one will be much less and if the Random Tech units hold up, I'll be good... If not, I will get another 2 years of use before another failure...

 

Not everywhere requires a vehicle to meet emissions requirements. If you are in one of those areas and can live with a CEL staring you in the face, you really dont need it.

OP: I see your point of trying to save money with just replacing the cat, thats why I'm helping you out. RMW's street header is avalible on Detroit Tuned's web site, or with a phone call to the manufacturer. They are a little more pricey but the service and support is worth it when your ALTA fails again. Last I checked, (and I know mine came with one) They use a Random Tec cat.

 

Running Mynes V2 header w/Miltek and no problems

 

I have been running a Milltek header for the past 40,000 miles with no issues.