[71 cuda]

i want a cut out system for my truck but someone said i had 3 cats is that true i cant see it

 

[Modain47]

My 2002 QC is a California model with three cats: one small pre-cat just after each side's exhaust manifold, and one large main cat after the y-pipe. I suspect yours is similar.

 

[AP]

Yep, I think thats true....sadly to say. Mine has 2 little pre-cats just underneath the ex. manifolds on each side and one right before the muffler....well at least I think it is.

 

[razman131]

3.... two little pre cats and a main cat. you should also have just 2 O2 sensors

 

[Compstall]

For an '03, you have 3 oxygen sensors; one before the pre-cats and one after the main I believe.

I need to go outside, but too lazy and too cold. So maybe I'm not much help here, but either way, some shops will not install a cut-out before any catalytic convertor due to Fed. reg's. Maybe find a buddy with some welding skills?

 

[Dustinmc15]

I have an 03 and it had 3 cats, two small pre cats right after the manifolds and a 3rd main cat downstream. I got rid of the 3rd cat and it doesnt throw any codes and still passes emissions.

 

[AP]

I have an 03 and it had 3 cats, two small pre cats right after the manifolds and a 3rd main cat downstream. I got rid of the 3rd cat and it doesnt throw any codes and still passes emissions.

Really, it doesn't throw any codes? You're talking about the one right before the muffler right? Since I took my muffler completely off and added a Y in it's place...I wonder if removing that cat would throw codes?

 

[Compstall]

If you modify anything BEFORE any O2 sensor, chances are high you'll get a code. Anything AFTER the rear-most O2 sensor doesn't matter.

 

[Dustinmc15]

^What he said^ Because the third main cat is already passed the rear 02 sensors the pcm has no idea wether it is there or not. You will not throw any codes if you completely remove it.

 

[AP]

I wonder what hp gains I will get and sound wise. Since I added the Shaker, I noticed a slight hp gain, throttle response and sound. Will back pressure be an issue by removing the 3rd cat since I have no muffler? Thanks!

 

[BRUISER QUAD]

I wonder what hp gains I will get and sound wise. Since I added the Shaker, I noticed a slight hp gain, throttle response and sound. Will back pressure be an issue by removing the 3rd cat since I have no muffler? Thanks!

If you are running the pipes all the way back to your Cuda bumper i'd say you'd have enough pipe for the needed backpressure to build.

If i'm wrong i'd like to hear cause i'm looking to go strait all the way to the back if i don't like the Magnaflow I've got on the way. and i'm only running the 2 cats before the Y.

 

[71 cuda]

hey yall thats great thanks alot im gonna have to get up there and look at it later gents

 

[BXER1]

I got 2001 QC with 4.7 and have three cats,two small ones and the large one before the muffler. Also have 4 O2 sensors which are located before and after the small cats. Will be replacing the OEM two small cats and wye pipe with a new wye pipe ( Magna Flow) High Flow cats,two magna flow stainlees mufflers which should make this a true dual exhaust. Not sure which mufflers will achieve what I'm looking for yet, but hope to improve performance,MPG also. Will update when completed.

 

[BRUISER QUAD]

Will be replacing the OEM two small cats and wye pipe with a new wye pipe ( Magna Flow) High Flow cats,two magna flow stainlees mufflers which should make this a true dual exhaust.

If you are wanting true dual exhaust, you need a H or X pipe..... a Y pipe blends the 2 headers into one exhaust pipe, look at the shapes of the 3 letters X, H, Y... self explanatory.