Exhaust Help

[milehighaz]

Hey guys...99 2DR Hoe with 4" Lift and 285 tires. I tow a toy hauler and am really looking for more HP/TQ whatever to get this thing towing better.

On the to do list already is 4:10 gears, Superchip.

I have an Air raid kit, and a cat back magnaflow muffler, single output.

Problem #1 is the high flow cats I have (not sure if they are magnaflow but I suspect not) is they trip my o2 sensors all the time. Been told that only factory cats will keep this from happening.

I want to redo the exhaust and wonder while I am here should I install headers or not? If so, is the pipe diameter going to change all the way back?

Second, which cats are known to not cause any sensor probs?

Thanks in advance.

 

[SunlitComet]

What do you mean trip your sensors? To got specific codes you could specify.

 

[foreverfalcon40]

Do not go any bigger then 2 1/2 in exhaust bc anything bigger then that with out FI you will loose power do to lack of back pressure.

B/c after market cats trip 02 sensors they are not garbage. There is spark plug fitting that can be drilled out and welded into the 02 bung to further pull the sensor away and not cause a CEL.

FYI I have 2 BNIB 2 1/2 in maganflow cats and used 2 1/2 QTP Electric Exhaust Cut outs for sale if interested.

 

[milehighaz]

I wish I had the codes...I know they were lean codes, and bank2 codes...They come and go, sometimes stored sometimes not. Just plugged in my superchip and they are not there. I will post when I find them. Everyone I have talked to said it was because anything other than stock cats will cause lean codes or o2 sensor codes to appear.

Yeah, PM with contact info regarding your magnaflows and we'll talk.

Thanks...
Paul

 

[992dr]

I have had my exhaust for a while, headers Maggy HF cats and Maggy muf. I have not had any codes.

Might as well do the rest, if you plan on keepin the Hoe. What are your plans?

Typically you replace all tubing with new larger diameter tubing. 2.5" seems to be the sweet spot for a stock or bolt-on motor. Or a 2.5" in and 3" single out muffler is also popular.

I have not heard of any cats throwing code, if thats the case. Magnaflow HF spun cats and oe replacement cats are al I buy. I have never had any codes or problems with either.

 

[milehighaz]

I have had my exhaust for a while, headers Maggy HF cats and Maggy muf. I have not had any codes.

Might as well do the rest, if you plan on keepin the Hoe. What are your plans?

Typically you replace all tubing with new larger diameter tubing. 2.5" seems to be the sweet spot for a stock or bolt-on motor. Or a 2.5" in and 3" single out muffler is also popular.

I have not heard of any cats throwing code, if thats the case. Magnaflow HF spun cats and oe replacement cats are al I buy. I have never had any codes or problems with either.

Yeah, I'm keeping her. Already put 10k in her in the last year or so with suspension and new engine.

Those codes happened with the old engine as well, and with new O2 sensors, so the cats are the only constant so that has to be it.

Stock 5.7....so with the magnitude of headers available, is there a particular that fits this installation best, that doesnt leak?

I'll go with 2.5" and magnaflow cats soon I'm sure. Assuming you are suggestion true dual all the way?

 

[992dr]

Yeah, I'm keeping her. Already put 10k in her in the last year or so with suspension and new engine.

Those codes happened with the old engine as well, and with new O2 sensors, so the cats are the only constant so that has to be it.

Stock 5.7....so with the magnitude of headers available, is there a particular that fits this installation best, that doesnt leak?

I'll go with 2.5" and magnaflow cats soon I'm sure. Assuming you are suggestion true dual all the way?

If I remember correctly I had a code thrown before my exhaust and after my exhaust. I believe it had to do with bank 2 also. I ended up replacing quite a bit of my emission system and that ended up clearing all the codes.

I think headers get a bad rep because of people who have not had them or read about them leaking. I have had headers on several cars and trucks I have owned, none of which leaked. I have Thorley Tri-Ys on my Hoe now. If you are planning on building a complete exhaust, I'd recommend LTs. That is what I would do if I had to do it over.

You can go duals or dual in and single out. Mine is a di/do muffler and I made a y pipe to a single out over the axle. I whipped it up because my father in law was coming and doesnt like loud cars, with it dumped under was pretty loud, inside and out. I'm planning on getting a dual in and single out muffler to replace what I have now and run a single pipe to the stock location.
Now, IF I had LTs. I'd run two pipes under each side exiting behind each wheel/tire. I have plenty of room to do whatever, thats what great about the 2wd tahoes.

 

[19Yukon97]

I wanna add to this. I have longtube headers and they dont leak. I also have 3 inch piping going to the muffler with 3.5 inch pipe after the muffler. I have no back pressure problems at all. I have Pacesetter LT's they are great! Magnaflow 3 inch in/out cats. The O2 sensors are in the stock locations. The muffler is a Flowmaster 50 series SUV. I dont see why people think that bigger piping causes problems with backpressure. There is no evidence to this anywhere. The only things i have done to my truck is electric fans, K&N filter, exhaust and a blackbear tune. No back pressure problems here.

 

[THE YETI]

Do not go any bigger then 2 1/2 in exhaust bc anything bigger then that with out FI you will loose power do to lack of back pressure.

say what?