Gen II Exhaust With & Without Cats

[Vipuronr]

So, been following the exhaust thread and asked about advantages/disadvantages of no cats vs using hi-flow cats. Trying to understand if there is any advantage to just taking the cats out vs. moving to hi-flow cats.

Also, if possible, any before and after sound clips based on removing the cats?

Thanks much.

 

[2001-V10 Power Nut]

I had Bellanger headers & exhaust w/high flow cats on my 2001. Increased HP & it sounded great !! Had a friend who had similar set up but without cats. I was very, very loud. I personally liked it, but it was very loud. Just depends who's in the car with you, or what kind of driving your doing

 

[CitySnake]

I had Bellanger headers & exhaust w/high flow cats on my 2001. Increased HP & it sounded great !! Had a friend who had similar set up but without cats. I was very, very loud. I personally liked it, but it was very loud. Just depends who's in the car with you, or what kind of driving your doing

That's pretty much it in a nutshell. Only additional item is that w/o cats (HF or OE) you'll have issues with oder and inspection.

The HF cats also tend to get noticeably louder over time as their insides burn up. After 5,000-10,000 miles, the HF's will be much louder, though you may not notice it as it's gradual.

 

[CitySnake]

Another benefit of catless is "flame throwing". But with a rear exhaust it's not nearly as noticable.

 

[Vipuronr]

Okay, thanks, I see the differences. So, Scott, is there any issue with emissions inspection and doesn't catless throw some kind of code in the computer?

NY/CT emissions seems to be fairly strict, so how would the car pass without cats?

Thanks much.

 

[MTGTS]

I doubt you could pass inspection without cats.

 

[plumcrazy]

mine passed NJ inspection without them. they wont be popping off any sills to inspect them. as long as the engine is running right, no CEL and within spec for emissions, its gonna pass

SC, no cats, 800+ rwhp here

 

[Ricketts]

mine passed NJ inspection without them. they wont be popping off any sills to inspect them. as long as the engine is running right, no CEL and within spec for emissions, its gonna pass

Bingo!!!!

 

[eucharistos]

what is your end game?

sound, heat, hp gain?

budget, diy-er

future mods?

we have sniffer testing here, so catless not an option for me

many ways to skin a cat (<-- ) depending on your answer to these.

the easiest answer always follows the phrase "money is no object" or "only the best"

 

[plumcrazy]

you can pass a sniffer test with no cats. i have done it recently.

but hoestly, no cats is probably too loud for most. if you dont have a boosted car, go with HF's if noise is a worry

 

[eucharistos]

you can pass a sniffer test with no cats. i have done it recently.

wow, that is good to know. if my hiflows ever burn up, i'll try catless, at least for a little while

 

[ViperTony]

Agree with Plum. Also, I read here over the years that owners replaced their cats with spiral flow mufflers to help control sound. Smell will always be there but I like the smell of rotten eggs in the morning.

 

[eucharistos]

if i knew then what i know now, i'd start with catless, stock everything else

the stock muffler is heavy, but good quality,

then i'd try gutting the muffler, to keep the stock look but lose some weight and add sound,

then i'd replace it with an x-pipe, which is close to the setup i have now (hiflows and x-pipe) and really like the blended sound, though the hiflows are still plenty hot

 

[Martin]

In my opinion, if you remove the cats, do it in a way that you can pop them back in if you need to. There are some disadvantages to removing them - will be much louder (may not be a disadvantage), will be STINKY, and you might fail an emissions test. Without the cats, you might pass the sniff test in some states if your car is in perfect running shape, but it doesn't take much to push it out of the OK window. Finally, if you go to sell the car, you'll need to put the cats back in - you don't want to get into a situation where a new buyer realzies that you pulled them - there are some federal and state laws against tampering or disabling emissions equipment. They could in theory force to you pay for whatever it costs them to bring the car back into emissions compliance - and that could be expensive.

 

[moparracing]

in wa state, they only check for codes - so passing without cats isn't an issue. All you need are a couple of cheap anti-foulers to fool the back o2 sensors.
I run w/o cats & magnaflow muffler/resonators in the sills for heat reduction (alot of it). I tried running a randomtech catback, but too loud, too hot & way too much resonance in the cabin along with the flame thrower decels. As a temporary fix, i removed the ramdomtech mufflers, put the maggie's in the sills & put the original back muffler on. Killed most of the cabin resonance & no more flame thrower...... I'm planning on a ballenger catback later to go with the headers already installed. It doesn't sound too bad for now.

 

[Russ M]

The #1 reason to remove the cats is heat, without them the viper turns into a different car which is a joy to drive even for prolonged spirited runs. With them you end up having to run the AC just to keep your feet from bursting into flames.

 

[CitySnake]

Okay, thanks, I see the differences. So, Scott, is there any issue with emissions inspection and doesn't catless throw some kind of code in the computer?

NY/CT emissions seems to be fairly strict, so how would the car pass without cats?

Thanks much.

Hi Peter,

Chuck would (obviously) be the best reference or those questions.

Regarding NYS inspection, the problem relates mostly to any CELs. As others have suggested, if you throw a CEL, you'll need to pull it and then drive for a while before you can pass inspection (100-200 miles, sometimes more and sometimes you need several engine shut downs and starts)-varies from car to car). So you want to insure that your inspection is some time after you pull any code.

Both HF cats and catless can cause CELs. Again, depends on the controller, the car and how you drive. Wizard is the best reference.

IMO, the ONLY reason to go catless vs. HF cat is for sound pressure (and exhaust flames). There's no worthwhile HP gain in going from HF cat to catless. Not much difference in heat reduction either.

 

[plumcrazy]

city taught me a nice trick recently, use a spark plug non fouler for your o2 sensors and no more CEL's.

thanks city !

 

[CitySnake]

city taught me a nice trick recently, use a spark plug non fouler for your o2 sensors and no more CEL's.

thanks city !

Can you be ANY cute'r?

 

[plumcrazy]

lol........

 

[eucharistos]

..... Not much difference in heat reduction either.

hey city, i have no 1st hand experience on the difference btw hiflow and catless, but have heard here that the difference is significant

 

[DrumrBoy]

Sill temps go down when the cats are gone....depends on your tune and headers whether you'd see a sill temp drop with HF cats.

Yeah, loud and stinky too. I like loud and stinky.

 

[eucharistos]

Sill temps go down when the cats are gone....depends on your tune and headers whether you'd see a sill temp drop with HF cats.

i'm have stock headers, roe metal substrate h/f cats and a roe 93 sct tune, and heat (much less than stock though) do you think i am running rich

 

[CitySnake]

hey city, i have no 1st hand experience on the difference btw hiflow and catless, but have heard here that the difference is significant

Could be. There's too many variables and it's too subjective to make any accurate determination. No doubt going from OE cats to HF cats reduces heat and going from HF cats to no cats will go further. Having had OE and HF cats in both a GEN 2 and 4, I can say that heat is no longer an issue with the HF cats. But of course, it all depends on how you drive and where you drive.

 

[eucharistos]

+1 on the where you drive

it really bugs me in the texas summers, not too bad these days, but summertime is embarrassingly hot

thanks for the feedback

 

[Vipuronr]

Okay, first thanks for all the feedback. To answer some of the questions, I want the car louder but not overly loud. I am not planning any heavy mode, no headers. Budget not an issue, but have 2 young kids so don't want to spend unnecessarily. Would like to reduce sill heat. I already have muffler delete, though the version with small bullet resonators near the tips. I thought, short of a complete exhaust change, this was the next best thing. Yes, have spoken to Chuck about hi-flow cats but not catless.

Thanks again.

 

[my viper]

Based on your response HF cats seem to be the way to go for you.

 

[Vipuronr]

Thanks, discussion was helpful!

 

[eucharistos]

.... I already have muffler delete, though the version with small bullet resonators near the tips. .....
Thanks again.

did you do it or was it on the car when you bought it?

if already on, do you know if it part of a catback system?

 

[plumcrazy]

he bought it used and had tator install it.