Cat or Catless Downpipe
 

I have a 09 MCS for my DD. Wanted to install a CNT downpipe, but I dont know if I need a catless or Cat downpipe. Also do you gain any HP from doing this bolt on mod?

CNT RACING VERSION 3 MINI COOPER S R56 R55 R57 R60 R58 R59 CATLESS DOWNPIPE

No experience on performance, but cat is better for the environment, and catless is better for your wallet. Spend the money, buy the one with the cat, and maybe our children will still get to drive internal combustion engine cars.

Cat-less will help a little bit with performance, but you will get an engine light. Catted will keep the engine light off, but won’t give as much performance. Any downpipe other than stock will require an a ECU tune to get all the benefits of the additional flow potential.

I sell catless and they make the most power when tuned. Let me know if you need tuning to complement your new mods
40-100hp gains with tuning depending on supporting hardware

Mario

mQubed Motorsport Manic & RPM Power Tuning

I bought the same one. It's now hanging in my garage as a reminder to spend money up front and buy quality first. The CNT was garbage, it didn't fit properly, leaked constantly and was poorly constructed. Mario's product is a world away from CNT. Do it right the first time 👍🏻

They will both give you power gains. The catted will tone down the sound a little though as I run the Akrapovic on my Clubman so I don't get drone on the highway. It is a perfect fit and has a 100cel high flow cat.
https://www.waymotorworks.com/akrapo...6-r57-r58.html

Afe is also making a quality catted DP now too
https://www.waymotorworks.com/afe-do...9-r60-r61.html

But for the catless I like the Milltek the best as the turbo flang and first 4 inches of the pipe are all cast as one piece to make it reliable and not have a weld on the flange.
https://www.waymotorworks.com/millte...-downpipe.html

Thanks for all the input.. I will save more money and buy a catted downpipe. As I dont want a check engine light or drone. Thanks again!

Catted downpipe will also be better for your lungs when you have the windows down.

will a Catted help with the drone sound on the freeway?

I disagree, I have the CNT and with some tweaking and taking the time to make sure everything fit, I don't have any leaks. That being said, I did have to do some slight modification to get the bottom end sealing up around the v-clamp. I ended up buying CNT's DP and the rest of the exhaust behind it and for the money, it was definitely worth it. Again, I had to do some modification to keep the leaks at bay and make it work "right" and if you want to spend the extra money on a better brand, you might not have to worry about these problems. If I weren't balling on a budget, I would definitely have gotten @MarioKart 's DP, but I would likely have still gotten the CNT exhaust pipe because it sounds pretty damn good butted up with a catless DP.

Regarding OP's main question, the power difference between catless vs catted won't likely even be noticed unless you get a tune. If you go for a tune and you want the most power, you're going to need either a high-flow cat or catless DP (that's as long as you live in an area where you can get away with it; no emissions testing). You may also want to do some planning and see about what your max budget is going to allow for a medium-term project, because if you get something now that won't benefit the rest of the build, you might have to replace it down the road. Do some research into if you're going to want to get over 230WHP and if you do, you're going to need some internal building and a (I think) slightly larger turbo. If you're looking for less than that, my build is currently roughly 230WHP with a catless DP, catless exhaust, a cone intake, a larger intercooler, a tune, and with the age and abuse now needs a clutch. Always with a build, you'll want to plan for unexpected expenses (like my clutch with mine), but get a good idea of what you want from the beginning.

Thank you for all that detail.... I had to put my savings into new tires, but exhaust is next on my list to do... If I plan on keeping the car or seeking a MCS JCW.

From the research I found. Catless will drone the cabin out. I can not say catted will have no drone, but I'm sure it has to be a lot better.

Catless definitely adds a drone, but from what I remember in the brief period before getting the rest of my exhaust, it wasn't unbearable. With the rest of the CNT exhaust, it's a very comfortable rumble (drone) cruising on the freeway but I absolutely love the sound. It's not too loud in general, but it will have a substantial freeway drone for sure.

I have a catless dp from Mariokart, with stock exhaust (for now) and it is a very pleasant sound. In sport mode you get nice pops and burbles, when not in sport mode you can hear the engine more, but it’s not an annoying drone, at least not in my opinion.

Why would you modify your car to emit 10x the pollution. I just can't understand that mentality.

At least I drive the Mini way more than I drive my Corvette with the 502, so that has to help some, right?

My catless downpipe on my Clubman didn't add any drone. It did add a little bit of volume, but still very livable. Wife didn't even notice.

Downstream exhaust has more to do with drone than the downpipe.

08 clubman catless down pipe, no drone, nicer sound and more power.

Unfortunately not everyone understands how rude and irresponsible it is to pollute another person’s air they breathe (no different than with cigarette smokers but at least there are public space bans in place to protect others). It is selfish, smelly and, to be perfectly clear, completely illegal to run catless but it is their freedom of choice to be deliberately illegal. Get a hi-flow cat, reputable tune and enjoy the result without being a stink bomb.

What is this forum’s policy regarding facilitating (and indirectly promoting) discussions of illegal practices? A majority of the other forums I have been a member of enforce a strict policy against it to, among other things, protect themselves from legal action as host facilitators.

Keep it clean out there and respect others and the environment.

The catless downpipes are sold "For offroad use only" so technically it is the responsibility of the person modifying the car. If you want to delete the cat from your track only car I'm fine with that. Deleting the catalytic converter from your daily driver is in my opinion not only rude, irresponsible, selfish, and stinky, it is one of the most anti-social things you can do. And so boy-racer. "Hey, I'm catless, woo!" Yeah, and you're a gross polluting fool. The argument of "one car won't make a difference" is a logical failure. Look up "tragedy of the commons".

My opinion is not universally shared by the membership at NAM, usually I just ignore threads like this. Every now and then after a couple of cocktails I speak my mind. About the only topic forbidden at NAM is street racing, those threads are whacked as soon as we see them.

Op, I hope you got the info requested to make your decision. On that note my time here has run its course, farewell all.

I got the updated CNT Catless DP and ive had no problems, fits perfectly

Yeah, I get the "polluting the environment" argument, and I agree to an extent. The main problem I have with getting a high-flow cat is the cost. If Indiana did emissions testing, which they don't, I would have to have spent extra money to get a high-flow cat. Regardless, the few of us that go with this option aren't adding any weight in comparison to the massive companies and their comparable CO2 emissions.

I doubt I'm going to change anyone's mind on the "my one car won't make a difference compared to all the other polluters" argument. Again, it's a logical failure, tragedy of the commons and all that. But if you want to see a real scientific study, check this out:

https://jamanetwork.com/journals/jam...stract/2733972 Association of Changes in Air Quality With Incident Asthma in Children in California, 1993-2014

It's a study just published in the Journal of the American Medical Association showing a correlation between reduction in Nitrogen Dioxide (what your catalytic converter cleaned up, before you took it off the car, and a primary contributor to smog) and reduction in childhood asthma. I grew up in Los Angeles during the 1960s when the air was brown with smog. I had asthma. If you want to know what that feels like, put a plastic bag over your head.

Getting rid of air pollution is like preventing litter, we all have to do our part. You'd be upset if I took my dog for a walk and let her poop on your lawn without cleaning it up. That's what all you catless people are doing to our air.

The comments above are my own as a member of NAM, and not as a moderator. They are my own opinion and do not represent the opinion of NAM or Internet Brands.