Cutting out Catalytic converters???
Thread Starter
Instructor
Joined: Dec 2004
Posts: 205
Likes: 0
From: Regina Sask
Cutting out Catalytic converters???
I have been reading about X pipes etc on here and am wondering about doing the following to my 99 vert. Can I just simply cut out the Cats and replace the section where the cats were with a straight pipe? Will this give me any performance gain or is there sensors etc that require the cats to be there? I live in an area where emission testing is unheard of so I'm not concerned with passing smog laws or anything like that. I love a deep sound and loud is nice as long as it's not obnoxious. Until I can afford a complete aftermarket system I was thinking this would be a cheap way to make a few ponies. What do you think? I was also going to go with a K&N with the air box mod or a Z06 cover for a few ponies there and the AandA mod to the exhaust. (adding the pipe to bypass the muffler) . Worth the $$$$ or a waste of time?
Thanks guys.
Rizzo.
Thanks guys.
Rizzo.
Last edited by Rizzo1; Dec 20, 2004 at 11:21 PM.
Tech Contributor
Joined: Dec 1999
Posts: 32,910
Likes: 2,402
From: Anthony TX
CI 6,7,8,9,11 Vet
St. Jude Donor '08
My cut on this is the following:
The CATs removed will only net you about 5-10 HP You will have to invest in SIMs for the after CAT O2 sensors and the noxius exhaust without the CATs will make your eyes water!
I just added Stainless works headers Random Tech cats 3' mid section with X pipe and 3" stainless exhaust. I was really impressed with the power increase and the sound!!
I recommend waiting and saveing your money to go all the way. Get high flow cats and stay legal.
Get a Fram Air Hog filter (a lot less money) and do the ZIP TIE Mod! You will be impressed! Make sure that you add a hood seal to keep out the water and dirt!
The CATs removed will only net you about 5-10 HP You will have to invest in SIMs for the after CAT O2 sensors and the noxius exhaust without the CATs will make your eyes water!
I just added Stainless works headers Random Tech cats 3' mid section with X pipe and 3" stainless exhaust. I was really impressed with the power increase and the sound!!
I recommend waiting and saveing your money to go all the way. Get high flow cats and stay legal.
Get a Fram Air Hog filter (a lot less money) and do the ZIP TIE Mod! You will be impressed! Make sure that you add a hood seal to keep out the water and dirt!
Drifting
Joined: Jul 2003
Posts: 1,313
Likes: 0
From: Redwood City, CA
Get this below. I plan on doing that to my Z06 soon.
http://www.superchargers4less.com/ba...oad_xpipes.htm
http://www.superchargers4less.com/ba...oad_xpipes.htm
Burning Brakes
Joined: Jun 2002
Posts: 1,097
Likes: 0
From: Muskogee, Oklahoma
I had the cats cut off a couple of weeks ago and am 100% satisfied. I have the GHL Magnums and the sound was not aggressive enough for me. A local muffler shop had a Magnaflow X-pipe that fitted in place of the stock H-pipe. This X-pipe is the short one about 12" long.
I then had them replace the cats with 2 short pieces of exhaust pipe.
Sound is much better. A little resonance at 1400 rpm, but goes away cruising 1500 and up. At around 2500 rpm when going through the gears, it roars. If my local shop did not have the Magnaflow, I was going to have them make an X-pipe to replace the cats section. A GOOD muffler shop can do this. Don't forget the O2 sims for the rear sensors. I say go for it, you'll be a happy camper.
I then had them replace the cats with 2 short pieces of exhaust pipe.
Sound is much better. A little resonance at 1400 rpm, but goes away cruising 1500 and up. At around 2500 rpm when going through the gears, it roars. If my local shop did not have the Magnaflow, I was going to have them make an X-pipe to replace the cats section. A GOOD muffler shop can do this. Don't forget the O2 sims for the rear sensors. I say go for it, you'll be a happy camper.
Melting Slicks
Joined: Aug 2002
Posts: 2,324
Likes: 0
From: central NJ
Mine are gone, with straight pipes welded in place. I think im going to random techs when the money comes up. Whenever I take the car out the clothes I am wearing smell like exhaust. Much like when I ride my streetbike. Doesnt really bother me, but people have noticed it.
Thread Starter
Instructor
Joined: Dec 2004
Posts: 205
Likes: 0
From: Regina Sask
So what are the 02 sims?? I've never heard of this before. Is this something I need to have welded into my exhaust system? 5 to 10 hp sounds good for a simple mod but I don't really feel like smelling like exhaust every time I drive the car. When you order a complete system does it eliminate the cats or do they keep the stock ones? Also. how much sound do you get from removing the cats? I like my cars to be a little on the loud side but not obnoxious.
Thanks guys,
Rizzo
Thanks guys,
Rizzo
Burning Brakes
Joined: Aug 2004
Posts: 837
Likes: 2
From: Derry NH
If stock cats only eat up 5-10 HP than what advantage is there in paying for high flow cats? Won't a high flow cat still cost 5 hp? Seriously, I am asking a question and not taking a shot at anyone else.
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Drifting
Joined: Aug 2002
Posts: 1,299
Likes: 0
From: Stanwood Michigan
Alot will depend upon your current setup. Every car is different and only a good day at the dyno will tell for sure. I can pick up 25HP with the cats off and this was verified at the dyno when the car was being finalized but it is against the law for a retailer to take off the cats so that is on my list of things to do this winter. My point is that a great investment is time at the dyno trying diferent things and finding the combination that gives you the best results.
Burning Brakes
Joined: Jun 2002
Posts: 1,097
Likes: 0
From: Muskogee, Oklahoma
Originally Posted by Rizzo1
So what are the 02 sims?? I've never heard of this before. Is this something I need to have welded into my exhaust system? ...... but I don't really feel like smelling like exhaust every time I drive the car. When you order a complete system does it eliminate the cats or do they keep the stock ones? Also. how much sound do you get from removing the cats? I like my cars to be a little on the loud side but not obnoxious.
I asked others about the exhaust smell and it is not on me. As far as the smell goes, my car just smells like an old hotrod when idling. It is not strong at all.
Some complete systems have high flow cats - some don't. I don't recall ever seeing a system where you reuse your stock cats.
The sound is not obnoxious without cats. I was really expecting my car to be louder than what it is now.
Safety Car
Joined: Aug 2000
Posts: 4,537
Likes: 84
From: St. Joseph MO
Cruise-In III Veteran
Cruise-In IV Veteran
Heads/cam, TTS longtubes, no cats, corsa x-pipe, and SLP loudmouth. It's loud and damn fun. The smell is slightly bad when its sitting in the garage idling. But hell, its my strees relief 
