Removing cats on 98 5.7l

[Dragit]

Iv been throwing around the idea of removing my cats on my 1998 z71. I know the check engine light will be on but thats no big deal. But Iv heard mixed reviews on performance some say Ill loose low end some say Ill gain all threw the rpms? So I wanna hear from some people running on cats on a 96-98 5.7l please. Also thinking of getting some headers at the sametime any brand prefrences?

 

[jcro61]

I personally dont think the cats being on or off will make a noticeable difference other than maybe the sound.
I always use Heddman headers, they are pretty cheap and last a decent amount of time. IMO any 500+ headers are a waste of money on a near stock truck.

 

[Southern Pride]

Well my question is what is the point of removing cats? Seems like all it would do is create trouble. They're there for a reason, unlike mufflers.

I have a tbi 350 that I just did true dual straights on. 2 seperate pipes with 1 cat on each (opposed to my old setup Y pipe with 1 cat which is better for low end torque) With the new setup I've gained a good noticeable amount of top end power. I have to go through inspection so I keep them plus it gives it just the right tone. If anything, remove the mufflers. I've yet to hear a muffler that sounded good.

 

[Dragit]

Main reason is mine are getting clogged up and would reather not spend my money on something thats gonna bog my truck down ya know. Im not too worryed about inspections around here. Plus they seem sound better without cats. Just not sure how they run tho? I had my truck strait piped after the cats and didnt really like it too clappy sounding for me.

 

[USAF_Slacker]

once you remove the cat and your ''check engine'' light comes on it puts your trucks computer into safe mode, which makes your truck lose performance because your computer is trying not to blow your truck up. once the cat is off and you weld in or clamp on your straight tubing to fill in the gap, youll need to tap that tubing and put a bung in there for the o2 sensor which im sure your aware of but, that engine light will remain on.

at this point you can do one of two things. find a little electronic piece (cant remember what its called) but you remove the o2 sensor and plug in this small electronic that mimics that your o2 sensor is running how it should and itll take the engine light off the dash. my buddy bought one for about $30 for his OBS. my favorite solution is the spark plug non-fouler. put the non fouler into the exaust then screw your o2 sensor into that and get your computer codes reset (autozone can do it for free).

problem solved!! a lot of info but i went through this headache for a week and it can get under your skin pretty easy

 

[slim]

or you could get a blackbear tune and have your rear 02 sensor "tuned" out like they were never even there. problem solved.

 

[1990GMCSIERRA]

if there the stock cats they are most likely stopped up and robbing ur ur exhaust
stopped up cats can cause alot of problems

 

[Dragit]

Yea I was gonna do the spark plug fouler trick v heard it works pretty good and I got a code reader so the engine light isnt a proublem. Just more worried about performance Im sure mine are getting clogged. Whats this Blackbear tune Iv heard about?

 

[Butch]

Black Bear Performance is a tuning company and a great one at that, Justin really knows his ****. Their website...

http://blackbearperformance.com/

The only way you'll see any performance gains off of removing the cats is they are already clogged which gives to much back pressure restricting flow. Most people that tell you their truck was stronger after pulling them off is mostly due to the placebo effect of the exhaust being louder, mine is much louder than I prefer with them off but needed to as both were bad. Someone mentioned earlier that pulling the cats will place the truck in limp mode, that I don't know about as its the first I've heard of it but I've never seen this in GMT400 trucks, it may happen in later models but in the 4 OBS's I've pulled the cats on not one of them have been put in limp mode. It will trip the CEL but the rear O2's only report that the Cat. Conv's are not working when checked against the upstream set and does not change up the air/fuel mix that the upstream O2's do. I've had my truck running with out the cats for roughly 2 years now and with no tune, simulators, or the non foulers, I've been meaning to try the non-foulers for a while but have yet to get around to it.

 

[DRAGGIN95]

I'd vote for removing the cat's!