High Flow Cat

[chrisyoung10]

Is it worth the $80 for a high flow cat to replace the factory cat?

[mobomelter]

80 bucks is cheap in my book. the high flow for my old focus cost almost 200 bucks. i mean given it was stainless steel....

[pdhaudio83]

no, its not worth it.

[TuRbOtEcTicS]

no, its not worth it.
why isnt it worth it? Seems pretty cheap.

[Captain KRM P5]

why isnt it worth it? Seems pretty cheap.

in my experience, if you are going to spend the cash to modify the exhaust system, make it as a free flowing as possible. even with no second cat in place, the gain on a naturally aspirated 3 is going to be marginal at best. so you see, switching to a hi flow cat won't net you much. i've been told by a few mazda techs that the 3's emissions system was designed to be as efficient as possible. like on the rx8, playing with the exhaust got people a max of 3 or 4 horsepower at best. modern exhaust systems are not only very clean, but very efficient as well - not like the big block v8 days of yore where an exhaust would net you 20 ponies.

that said, going with an intake, catless exhaust with a header (yes i know, none exist yet) as a combination will make a more noticable difference.

[chrisyoung10]

is it legal to take off the 2nd cat?

[goldwing2000]

is it legal to take off the 2nd cat?

Therein lieth the rub.

NO! It is not legal to remove emission controls on a road-going vehicle.

A high-flow cat may give you minor gains but on the flip side, it will give you minor losses to stay legal.

True, you may never get caught. But what if you do?

Besieds that, your dealer would be well within their rights to void your powertrain warranty if you removed any emission controls. For that matter, they could do the same if you modify the system but they're more likely to be lenient if they see you're making an effort.

[mobomelter]

of course if you live in maryland emissions testing consists of them plugging in your car for about 10 seconds then telling you that you passed. in md as long as your car isn't throwing codes, is obd 2, and isn't smoking, you pass.

[tgv121281]

Exactly, it depends on where you live....for example..I live in Florida and there are NO emission tests/laws.......as long as people behind you can see....it doesnt matter whats coming out of your pipes........I'm going w/ no cat, but I ordered the hi-flow anyway b/c I dont want it to be too loud.....When I receive my system I'll see if I like it w/ no cat...if so I'll sell you the Hi flow for at least 1/2 of what they are asking....Its a Draxas system by the way, they are expecting to ship them out on Feb. 7th, so sit tight if you want...hope this helps

So basically it 1st depends on emissions in your state, and then its up 2 you

[goldwing2000]

Removing emissions controls is against Federal law.
Just because your state doesn't have emission testing, doesn't make it legal to remove the cat.

[pdhaudio83]

its a $10,000 fine btw.

and yet, i run catless.

[mobomelter]

I'm going w/ no cat, but I ordered the hi-flow anyway b/c I dont want it to be too loud.....

trust me the high flow cat won't make it any less loud than no cat at all. when i put a high flow on my focus it made my nice borla muffler sound like rice.
also with the federal law thing if anyone actually got fined there would be ALOT less honda civics on the road near me..... considering they think straight pipes with can mufflers are "the coolest thing ever"
i realize it is illegal but the chances of getting fined are very low. the only way i could think of getting caught for no cat is.... smuggling drugs and they broke out the mirror... or rolling your car and getting it stuck on its roof.

[Captain KRM P5]

its a $10,000 fine btw.

and yet, i run catless.

so do i

[goldwing2000]

You're entitled to do whatever you want, of course. I'm just pointing out the law because the question was asked.

[Captain KRM P5]

You're entitled to do whatever you want, of course. I'm just pointing out the law because the question was asked.

oh i am not calling you out or into question for that, i hope i did not come across that way at all

[Greenbread]

ok sorry to jack this thread but i need to no before i order and i figure this thread already has to do with this. im getting a draxas exhaust. i live in ohio were there is e check. should i get just hte exhaust and leave the 2 stock cats, get the high flow or get ride of the second one and just get the catback. im going for performance and not ricey

[mobomelter]

performance wise you won't notice the difference. as for the e-check it depends on the type they do. it could be tailpipe or it could be obd type. obd type meaning they plug your car in without doing the tailpipe test. find out before you remove a cat.

[Greenbread]

but will it sound ricer

[mobomelter]

most likely with the extra flow it will probably sound ricey. suposedly a resonator will help tune the exhaust down. i never got that far with my focus since it was sold shortly after i put the headers and hi-flow pipe on it.

[curacer1]

does anyone know if the cat is obd2, which i guess means that the o2 sensor is in the cat or not, i get my exhaust in next week but need a cat

[mobomelter]

usually they put at least 1 o2 sensor before and after the cat. i have no idea what they've done on the 3 since i haven't been under it yet.

[AzMz3]

usually they put at least 1 o2 sensor before and after the cat. i have no idea what they've done on the 3 since i haven't been under it yet.


I don't think you know what you are talking about.
There is no sensor after the last cat, it can be removed without a CEL.
And you will notice a difference when switching to a hi-flow cat.

[mobomelter]

usually they put at least 1 o2 sensor before and after the cat. i have no idea what they've done on the 3 since i haven't been under it yet.
please read carefully before you insult someone. i said "usually" meaning on most cars i've seen. also i specifically said i had no idea what they've done on the 3. please read things before you make conclusions.

[CarbonMz3]

the o2 sensor is before the second cat, and yes you will get a little hp/tq out of it when you take out the cat, however, if you have CAI, header, and free flowing exhaust you get a noticeable difference. You won't feel a tremendous change by changing one thing, but as a whole it is a great gain. But going back to the topic, after I took out my second cat, I felt a noticeable change in power in mid range(3000-6000 rpm).

[goldwing2000]

I did and like I stated you don't know what you are talking about.

Herb, you were kind of an asshat about it. Try to be a little more civil, k?

[saskmazdaman11]

There are so many ways to run a cat illeagally, but still have the illusion of being legal. Those damn catalytic converters are so fragile, when you "accidently" drop them numerous times on concrete and then all the guts fall out. Or when you accidently cut the cat open and run the exhaust through it by mistake.
You may not pass an actual emmisions test, but it should pass a visual test.

[tgv121281]

Guys, can someone clarify this discussion.....here's what I'm getting out of this...with the Hiflow cat you wont notice hardly any diff, unless you have the intake, exhaust, headers, etc...once you have all that then the diff is there....Also, does the hiflow make the note ricey?????

[goldwing2000]

Guys, can someone clarify this discussion.....here's what I'm getting out of this...with the Hiflow cat you wont notice hardly any diff, unless you have the intake, exhaust, headers, etc...once you have all that then the diff is there....Also, does the hiflow make the note ricey?????

It's the same story with any minor modification. If you do one small thing, it will help. If you do other things related to that one thing, it will help more. It all depends on how much money you want to spend and how much you want to dig into your vehicle.

With regard to the note, a catalytic converter is a HUGE exhaust restriction, so it seriously deadens the exhaust noise. By putting on a high-flow cat, you are decreasing the restriction, thereby allowing more noise through to the rest of the exhaust system. Without the right muffler, this could end up sounding like a fart can.

[Greenbread]

so if i get an cai, high flow and a catback it wold sound good?

[mobomelter]

Without the right muffler, this could end up sounding like a fart can.
as goldwing said it depends on the muffler. my focus had headers, a high flow cat, and cat back exhaust. it sounded ricey but a resonator can fix the rice sound.

[CarbonMz3]

I can testify to the FACT that the 3 will sound RICEY with CAI, no cat, and 2.75in pipping straight through a muffler....(If i get a digital camera, maybe than I can let you hear and see what it sounds like. RICE! Yes I admit, it is really loud, and a little ricey)

[AzMz3]

I can testify to the FACT that the 3 will sound RICEY with CAI, no cat, and 2.75in pipping straight through a muffler....(If i get a digital camera, maybe than I can let you hear and see what it sounds like. RICE! Yes I admit, it is really loud, and a little ricey)

From the 2.75" exhaust I take it you have a custom one.
I'd agree if you go out to be cheap and get a crush bent exhaust with only a muffler and remove a cat, yes it will be pretty loud and sound bad.

The cats actually quite the exhaust down alot. I know when I added a off-road pipe to my Focus it was loud and pretty bad.

[tgv121281]

yeah but I ordered mine as all 1 piece, so why would it not be the "right" muffler??? not trying anyone, just dont really get it...if I order a catback system--I expect the pieces to be right for each other,(muffler, cat, piping)...I dunno, too late to cancel anyway so I'll just have to put it on and see whats up w/ it....I have a cai as well...so at least even if it sounds bad I'll have a pretty well breathing engine..till those headers finally come out!