Viper Scot
Viper Owner
I was just wondering what sort of power increase I'd get by removing the cats on my car? It's a '96 RT-10 with a Corsa system and high flow cats right now. Other mods are roller rockers, cam, headers, head work. Cheers
How much extra power by removing cats?
- Thread starter Viper Scot
- Start date
dave6666
Enthusiast
My guess is 5 to 10 hp. Sometimes the lack of back pressure can be detrimental though reducing hp. You gonna try to kill a few more mosquitoes when you drive around now?
Have you tried the search feature yet to research that topic?
Have you tried the search feature yet to research that topic?
SylvanSRT
Enthusiast
i have heard the same 5-10gain(but prob more like 5-7) removal of cats also will save a little weight, and best part is you get a flamethrower for free
Asp Man
Enthusiast
Would be more detrimental to low end torque than hp, which you'll not notice in the seat of the pants. Probably gaining only a few hp on the top, but the difference in sound will make up for any precieved loss in power.
-car runs cooler (at least in cabin temps/side sill temps)
-sounds better (imo)
-drop a few lbs. (easier than dieting)
-car runs cooler (at least in cabin temps/side sill temps)
-sounds better (imo)
-drop a few lbs. (easier than dieting)
SSSSE YA
Enthusiast
Searching before posting is a good idea, but on the other hand there may be newer information that has not been posted yet on a particular subject...
I see to many short replies that only say something like HAVE YOU DONE A SEARCH
instead of adding info.
Myself, I'm all for a thread that might yield replies with new info. There is more out there than what's been posted on already..
I see to many short replies that only say something like HAVE YOU DONE A SEARCH
instead of adding info.Myself, I'm all for a thread that might yield replies with new info. There is more out there than what's been posted on already..
Disturbed
Viper Owner
By replacing each cat with a pipe my car lost 6lbs. Not a huge loss but it is some. Butt dyno says I picked up 10hp. I picked up .25mph in the 1320 test.
It sounds so much better without cats. Loud, but better.
It sounds so much better without cats. Loud, but better.
Viper Scot
Viper Owner
Thanks for the advice folks. 10 hp is 10 hp in my book which, along with a little less weight, flames and more noise, is all good. Next question: where can I get some good cat replacement pipes?! 
Mccarlin
Enthusiast
Thanks for the advice folks. 10 hp is 10 hp in my book which, along with a little less weight, flames and more noise, is all good. Next question: where can I get some good cat replacement pipes?!
There are a few Cat removal posts on here with lots of details but what i did was cut the cats off the car, right after the welds and i measured the opening. I went to the local muffler shop and had them cut me some 3" straight pipe and expand the ends 2" or so to fit over the existing exhaust, then used some exhaust clamps. The opening is roughly 17-20" of piping on each side depending on where you cut. Cost about 40$ total and took under an hour to do
As mentioned, the extra HP and sound alone was WELL worth it.
Viper Scot
Viper Owner
Thanks again for the info. I've also done a search on previous threads and I was wondering what would need to be done regarding O2 sensors on a '96 RT-10? Am I going to have problems with the engine management system getting confused? Thanks in advance...
Viper Scot
Viper Owner
Anyone got some advice?
Chuck 98 RT/10
Enthusiast
I haven't heard of any O2 sensor problems when removing the cats. The sensors are before and aft and the engine apparently adjusts.
V10SpeedLuvr
Enthusiast
dave6666
Enthusiast
Sooo, what does one do with the cats when one removes them? Grind 'em up in to tasty burger meat?!? 
Disturbed
Viper Owner
Thanks for the advice folks. 10 hp is 10 hp in my book which, along with a little less weight, flames and more noise, is all good. Next question: where can I get some good cat replacement pipes?!
NAPA, be sure to use the 3" wide band clams...they work the best.
Disturbed
Viper Owner
My 01 GTS ACR has O2 simms in it. Check engine light does come on.
There are already posts on this but in the spirit of providing data you might want to take a look at the applicable federal and state law consequences of removing undamaged OEM cats for on road use. After you do, you might wish to clarify your post as to whether you intend to do so for on road or off road use.
Flyntgr
Viper Owner
I removed the stock cats and added 3" pipes with Borla mufflers to my RT/10 Gen. I, all for less than $500, and the car revved MUCH quicker, sounded much better and added 45-50 rwhp according to my Butt dyno. Much different car with these mods. You can get the 3" pipe from J.C. Whitney and the Borlas from any number of sources, including Jeggs. Try it; you'll like it, if you don't mind a much louder exhaust. If you don't want much louder, do what I did, but use the stock mufflers (ugh).
DrDJ
Enthusiast
To reinforce what BobPantax said, it is illegal to remove undamaged cats from your car, even if you replace them with hi-flo cats. Putting in straight pipes just goes too far. There are a number of excellent hi-flo cats out there to chose from.
There is no way that I would recommend that anything from J.C. Whitney be placed on a Viper. They only carry the cheapest of the cheaply made items. I would expect any exhaust piping from them to las about 250 miles.
DrDJ
There is no way that I would recommend that anything from J.C. Whitney be placed on a Viper. They only carry the cheapest of the cheaply made items. I would expect any exhaust piping from them to las about 250 miles.
DrDJ
Wow, if chopping off some cats "just goes too far" then I really don't want to mention some of the other illegal things I've done in my Viper.
Any who, for you guys that have already done this, how bad is the smell. That's the only thing I'm concerned about. With OBDII, as long as the check engine light isn't on I'll pass emissions.
Viper Scot
Viper Owner
Please note that I'm in Scotland, not the US! Laws are very different here. As long as the car passes emissions (and there are ways
), you can do what you like.Surely though you don't need to buy aftermarket cat replacement pipes? Would some 3" stainless pipe not do? There doesn't seem to be anything too complicated in the exchange from cats to straight through pipe...
One niave question though, what are 'sims'? Cheers.
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99 R/T 10
Enthusiast
Sims are O2s that simulate the second or rear set of oxygen sensors imput to the computer. On cars 2000 adn later it is necessary to have them otherwise the computer will throw codes.
I don't have any bad smells a from my car. One of the first things I did and as long as the car is running properly, it should be no problem.
I don't have any bad smells a from my car. One of the first things I did and as long as the car is running properly, it should be no problem.
Viper Scot
Viper Owner
So presumably my '96 RT-10 won't need sims then? As far as I'm aware, my car doesn't have O2 sensors in or after the cats...
All Blue ACR
Enthusiast
Where does one get these "Sims" and what's the procedure?
Disturbed
Viper Owner
butt dyno says 5rwhp....but make sure if your car is newer than 96, get simms or reporgramed ECU.
mjorgensen Woodhouse
Enthusiast
Of course you will gain a few HP removing the cats (although illegal) but ONLY on the very top end. You will see a loss through the meat of the power band you use all the time "under the curve" as dyno operators call it. Not a good trade in my humble opinion.
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