Catless vs. hiflow cats

[V10SpeedLuvr]

I'm getting real close to deleting the cats on my Viper. Would it be better to go with hiflow cats or completely catless? I'd like to hear opinions for both sides. Ive heard going catless will make the car run way too rich and have a badddd gasoline smell. Noise level is not a concern. IMO, The louder the better, but I dont wanna possibly damage anything else on the car just for a few decibels more of noise. What else will be affected (for the good or bad)? HP, gas mileage, etc? If it matters, I've already deleted my muffler and replaced it with straight pipes

 

[Camfab]

Just put high flow cats in. It's going to get nice and loud, you'll pick up a few horses and you won't catch the rear fascia on fire. No smell and, if you care... less pollution.

 

[big-n-italian]

i didnt really notice any smell difference after i took my cats out.

i did however notice alot more soot on the back of the car.

 

[Bob K]

I went with high flow cats first and really liked the sound (headers and old style Borla cat back). With this set up I dynoed at 445 rwhp. Last year I took the cats off and put a short piece of 3" straight pipe in. It was significantly louder and still deep sounding until WOT. At WOT it cackled more which I wasn't too crazy about but can live with it. I did notice that the smell increased significantly. No check engine light came on (I did add rear O2 sims). The good news -- it just dynoed at 467rwhp and 507 torq. with no other mods except K&N's and Henne$$ey air box.

Bob K

 

[Russ M]

The removal of cats is going to elimenate most of your side sill heat, which is the main reason you should be doing it.

Removing the cats has no effect on your air/fuel, but it will cause a bit of a smell if you sit still for a long time.

I have done some dyno testing with a viper of no cats and high flow cats and the results were identical. So far as power is concerned.

 

[JonB]

Catless can = some CONS:

8.0L of STINK every 2 rpms. Worse in sidepipers, or in slow traffic.

backfiring

Soot and even FLAMES, esp in sidepipes.

"Ratty" combustions sounds vs mellow. Sounds like a $100 kids pickup.
Worse in sidepipes.

OBD-2 problems, (not for your year)

Not ENOUGH backpressure if you have a straught-pipe sys = torque loss.

Can become a cop magnet


Catless, some Pros:

Cheap Loudness...or, loudness, cheap
A bit cooler than hi-flow cats. Not much cooler.
No one stands for long beside a sidepiper, or behind a rear exit.
Better flow and HP than OE..... but maybe not better than HF.

 

[Mark Hahn]

On my '96 I went Catless with the newer Borla exhaust which has the side mufflers and the combined rear muffler. I just purchased some straight pipe from Racers Wholesale and had it ceramic coated and used some of the newer stainless band strap clamps from them also. The sills are much cooler (although with only a 17" straight ceramic coated pipe I don't think the ceramic coating can take much credit). My has a little bit of small rumbling on deceleration until the deceleration fuel cutoff kicks in. I dont' think with the Borla setup that mine sounds 'ratty'. I have had many comments that it sounds much better than stock but I also installed an NOS set of ****** Headers at the same time. On the road I don't notice it being any louder just more at idle but not obtrusive like many, just a little louder and better sounding than stock, deeper. MGH

 

[Big Medicine]

There is a reason cats were not installed on older cars.

There is a reason they had to make it a law.

There is a reason race cars don't run them.

They are inefficient restrictions, counterintuitive for the pupose of an engine, and offer no benefit other than reducing unburned hydrocarbons (UHC) from the exhaust.

Motorcycles, ATVs, and lawnmowers certainly don't have them.

 

[2000gtsgsxr1000]

Get rid of them tampons! I can't believe there isn't any power increase.They can and will go bad and you don't want to buy them.I cut mine with a Borla and was told it was the best sounding Viper they had ever heard.I think it rocks.

 

[2000gtsgsxr1000]

I just saw toasted side sill post-nuf said.

 

[V10SpeedLuvr]

I'm leaning towards high flow cats. Anyone have a set of Roe HF cats lying around they wanna sell?

 

[ViperJames]

I'm leaning towards high flow cats. Anyone have a set of Roe HF cats lying around they wanna sell? [/quote

I agree this is the way to go...I couldn't be happier with my Roe HF cats

 

[DrumrBoy]

If your side sills aren't blisteringly hot when idling in the summer, then go with high flows. I was concerned that the sills would blister/melt because mine got so hot. Tried hi-flow cats and had onlt a slight improvement.

Removed the cats and now you can put your hand on the sill any time except for after some power runs. It really really helps the sill heat issue. Smells a bit more like gas (I say so what) and I do get more soot on the back. No problem if you wash it frequently.

If you have a heat issues, its worth tryin.

 

[JiPi]

Your car came stock with no resonator. Since you already deleted the rear muffler, if you delete also the cats, you will be running straight pipes all the way! It's ganna be VERY loud. As you said"The louder the better" but that's maybe too much. I thing HF cats are better.