There is still one cat near the downpipe. Header is stock. Ill go back to the shop and see what they say.



So theres a o2 sensor in the centre cat? The shop said removing the centre cat will aid im hp/airflow tho

 

The first O2 sensor tells the car what to do with fueling. Then the first cat cleans up the exhaust. The second sensor tells the car how the first cat is doing and the second cat is a secondary scrubber.

 

Is there a o2 sensor in the 2nd cat? The one in my first pic?

 

the second 02 is mounted below the first cat, the first 02 sensor is mounted above the cat.

couple scenarios here.

1. the rear 02 sensor might have been damaged during the install, wiring melted due to welding, or actual sensor damage.

2. rear 02 sensor is clogged or not sensing correctly.

3. its working but installed improperly, loose, crooked, not all the way in...





questions for you.



do you have the check engine light on?

are the backfires LOUD BANGS? or multiple little pops?

 

Thanks for the info! Just a farty noise if i floor it past 5000 rpm. No loud pop.

 

If you have a farty sounding exhaust it could be normal. Are you able to post a sound or video clip?

 

I agree.



You have 2 cats? I wouldn't take out any catalytic converters. They are like $700 each, and if removed will cause a CEL.



If you want better airflow you have to replace the cat (or both) with a high flow, but one with the bung already in after the cat, something like this:

It has to be rated your load capacity too, so under 4,000lb or commercial use. Some are rated for 6,000lb, so those would be for Trucks and SUV's.



Right now, if you feel uncertain with cat removal, stick with what you got until you research it a bit more. Otherwise you will end up with problems and waste money rushing into it.

 

The centre cat was removed as shown in the first pic. That's the centre cat that was on with the stock mainfold. There is no centre cat in the new cat-back exhaust system, only one cat remains which is the stock cat near the downpipe.



I'll post a sound clip soon!

 

[media]http://s823.photobucket.com/albums/zz159/slugzkea/Custom%20Cat-Back/?action=view&current=IMG_1391.mp4[/media]



Sound clip

 

do me a favor.



start the engine. let it warm up for 60 seconds. floor the gas pedal until you hit the redline. let off the gas until revs drop.



record that procedure.