Upgrading exhaust

[westman]

Well folks, tax time is quickly approaching and I'm looking to upgrade. I'd like to concetrate on the exhaust for my 99 Yukon SLT 4wd and was hoping to get some opinions. My ultimate goal is to improve the overall efficiency. Before I go diving into the system, I had a few questions first.
When searching for headers, I notice options for With or without AIR injection. How do I tell if I have AIR injection or not? Does it really matter? If I do have AIR injection and don't use it, will it throw trouble codes?
Does modify the cats or deleting them throw codes? As for catbacks, who makes the best, but still keeps noise levels managable?

 

[ivin74]

All 99s have the air injection. If you delete the cats you are going to get codes. FYI from my past experience if you are adding headers delete the air injection and add high flow cats and be ready to spend the money to get you truck tuned because you are going to need it.

If you want a muffler w less drone stay w Corsa or Borla

 

[westman]

Ivin74, thanks for the info and advice!

 

[Gzes]

Imo if your in a no test state chop cats and run non fouler and some long tube headers

 

[TigerEyz3]

All 99s DON'T have secondary AIR injection...in fact most don't. CA vehicles were most typically the ones that have secondary AIR injection.

To tell if you have secondary AIR injection, you'll have to either look in your glove box and decipher the codes or look under the hood of your vehicle and determine if you have an AIR injection pump (driver's side above the wiper fluid tank) and a manifold/header connection (front of passenger side tube).


If you don't have a CA emissions equipped vehicle, you most likely don't have an AIR injection setup.

 

[jerryjoe28]

i had my tunner turn my rear o2 sensors off. no cats and no codes