Hi-Flo cats for SC viper?

Skeeter Blanton · May 14, 2010

Recently purchased 01 Roe SC car (5 lbs boost) that has a corsa and stock cats....Previous owner did not want the car to be loud and I feel the same...Is anyone running Random ceramic cats? I understand they are quiter than metallics but there is a possiblity if the tune is rich the ceramics will not hold up...I will not be tracking this car, just profiling and on occasion some heavy street action....Any suggestions on how to add cats, have the exhaust not much louder than the Corsa tone and not have a failure? Thanks for your suggestions....

plumcrazy · May 14, 2010

Ditch the cats all together. Put an extra muffler in if you want quiet.

ViperTony · May 14, 2010

Neither is quieter than the other. Your best bet is to sell the Roe to me and keep your stock cats.

Skeeter Blanton · May 14, 2010

ViperTony said:
Neither is quieter than the other. Your best bet is to sell the Roe to me and keep your stock cats.

Thanks but no thanks....This one stays......

pedro · May 14, 2010

I have two muffler on the sides still load,Turbo are the way to go!

SquadX · May 14, 2010

Do as plum said or use the stock cats and cut the secondary. I had Random Tech hi flows and a supercharged paxton and they lasted 6k miles. had them removed and got roes hi flows. Mixed feelings on the sound (B & B full exhaust), especially under 3k rpms.

With Cats and a supercharger, as I was informed, they can, if not checked, lead to an engine rebuld.

Skeeter Blanton · May 15, 2010

Sounds like more trouble than its wort..... Think I will add 3:55's, leave the stock cats and the corsa exhaust.....Thanks for the input

plumcrazy · May 15, 2010

Good move. Stock cats or none at all !

KNG SNKE · May 15, 2010

Skeeter Blanton said:
Sounds like more trouble than its wort..... Think I will add 3:55's, leave the stock cats and the corsa exhaust.....Thanks for the input

Leaving your stock cats is a very bad idea. Your stock cats are designed to flow stock levels of air through them. You have another 2.4l of displacement to your motor. Your air flow is significantly higher. You will highly regret keeping them there in the future. Put high flows on them and stay safe.

FWIW When I added headers and removed the cats the car at idle was only slightly louder but much deeper. I run M&M headers 3inch catless corsa 5lb roe.

Skeeter Blanton · May 16, 2010

KNG SNKE said:
Leaving your stock cats is a very bad idea. Your stock cats are designed to flow stock levels of air through them. You have another 2.4l of displacement to your motor. Your air flow is significantly higher. You will highly regret keeping them there in the future. Put high flows on them and stay safe.

FWIW When I added headers and removed the cats the car at idle was only slightly louder but much deeper. I run M&M headers 3inch catless corsa 5lb roe.

Hi K.Snake......When you say I "will highly regret" leaving the stock cats, do you mean that because of the restrictive flow I am losing Hp & torque or that the stock cats possibly could break up? .......

plumcrazy · May 16, 2010

HF's are more likely to breakup or melt than the OEM im told.

probably lose some power with OEM but i was told stock cats or NO CATS.

KNG SNKE · May 16, 2010

The stock cats on the Viper are big, very big. They are warm, extremely warm. They are designed to flow stock air and fuel levels. By adding more fuel and more air to a restrictive point on the stock exhaust you will create a backup in your exhaust system. The exhaust will hang around the cat longer, heat up, break down the cat and will become a fire hazard for your Viper. Please search through this website for photos of catalytic converters failing. It's not a pretty site. If you want to keep the noise down, put hi flo's on your car.

Taken from the first page of the Roe Supercharger Installation Instruction
"The Supercharger kit is for off road use / demonstration purposes only and we strongly recommend no catalytic converters or high high flow catalytic converters when using the system. Stock "cats" are designed for the stock engine. The engine performance and air to fuel ratio with the Supercharger can surpass the capability of the stock converters."

MacManInfi · May 16, 2010

I run RT's on my Paxton car and have for several years. I did loose one once because I had an O2 sensor bite the dust. Not really the fault of the cats. Other than that, they have worked great for me.

TAXIMAN1 · May 17, 2010

I have to disagree with some of the above comments. Skeeter, I would definately NOT remove the cats. On my solid Yellow 2001 I tried this... Drove the car all of 5 miles, before I realized it was a mistake. The car sounded terrible (loud, and not even a good loud if you know what I mean, way too much resonance around 2k RPMS, it was really awful). I ordered Ceramic Random Techs from PartsRack, and the car was perfect after that. Yes, slightly louder than with the stock cats. But it was a clean, healthy sound to it..

For me, the stock cats just got way too hot.. The 3' Ceramic Random Techs with the Corsa is a great setup.

ViperTony · May 17, 2010

Give Chuck Tator a call....he's installed well over 100+ Roe kits and guide you in the right direction. 914-763-3136.

Purdue_Boiler_Viper · May 17, 2010

I've got an 01 Roe SC car as well. I put the RT high flow cats in even before the SC. Zero problems with the RT cats. The MUCH lower side sill temperatures is a big big plus. No more burning your leg getting out of the car. Sounds better as well. High flow cats should be one of your first mods, just due to the lower side sill temperature.

RTTTTed · May 21, 2010

My first Roe was HiFlow cats from Roe Racing and an 8# Roe with water/****. No problem.

Next I had NO Cats, headers, 10# Roe, 9-1 pistons, 1.7 rockers, 708 cam, Corsa Track exhaust. VERY Loud and I get compliments on the exhaust sound all the time. I love it! Corsa track exhaust.

Now I just bought a Paxton with Nitrous, Hi flows and Corsa 3" street exhaust. Very quiet, no compliments because it is quiet and again NO problems.

Stock Cats have overheated so bad that they've lit the fiberglas on fire. Factory wouldn't even use 4 chamber Cats - EXCEPT THAT IT'S A GOVERNMENT REQUIREMENT. Very restrictive and the first modification should be to removed those garbage pieces. Hiflow cats still cause restriction to the exhaust.

ALL Forced Induction are restricted by any and all exhaust systems. Headers get more hp improvement with FI than with n/a. Restriction on intake side of engine - increase boost. Restriction on exhaust side of engine - BAD when supercharged.

Ted

RTTTTed · May 21, 2010

On a personal note I agree with Plumcrazy and the first mod to any Viper should be to removed the Junk Cats. Imagine - 4 chambers! Wife's Hemi had smaller Cats and they were 2 sets of 3" long materials in a cherrybomb type chamber. My Stealth TTs came with 3 extremely deep restrictive Cats for a 3L V6! They succumbed to a 1 1/2" wood drill and long handled chisel. The Hemi has less retrictive Cats that most hi flow cats. If you want stock - use a set for a 08 Hemi Ram.

Ted

JKVIPER · May 22, 2010

Skeeter Blanton said:
Recently purchased 01 Roe SC car (5 lbs boost) that has a corsa and stock cats....Previous owner did not want the car to be loud and I feel the same...Is anyone running Random ceramic cats? I understand they are quiter than metallics but there is a possiblity if the tune is rich the ceramics will not hold up...I will not be tracking this car, just profiling and on occasion some heavy street action....Any suggestions on how to add cats, have the exhaust not much louder than the Corsa tone and not have a failure? Thanks for your suggestions....

I had the Corsa on a 2001 GTS non-SC car. Then swapped the stock cats for the Roe Hi-Flow. A very big difference in how much louder the car was. If you decide to get hi-flows, just keep the stock cats in case you want to reverse the swap.

Hi-Flo cats for SC viper?

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