you'd want to turn the rear O2 sensors off in the tune.

 

Not sure on a part number but a quick search on ebay should do the trick. I bought mine off ebay as well. A tune will be needed regardless of what brand of header you end up with. You can drive with out a tune, just dont expect much in terms of power until you get tuned. Obx long tube header 5.3 | eBay

 

Thanks everyone. I appreciate the help. I was able to find the headers for the avalanche, but wasn't sure if the fitment was the same for the silverados. As far as tuning goes, who would you recommend? I was looking at black bear, but it seemed that the up front cost for the data logging tune was quite expensive.

 

Personally I've been extremely satisfied with BB. Great performance and drivability, a couple of followup adjustments based on further data logging, and the ability to stick the stock tune back in at any time. Hard to beat - but I can't give you a direct comparison with other tunes. There are lots of happy guys on here with tunes from other sponsors.

 

I cant remember which site it was, possibly gm fullsize, but it was dyno proven shorties give 8HP and LTs give 21 HP so the math is pretty simple (unless that site was wrong). I regret buying shorties, look cool but I was uneducated and impatient.
I can vouch for BBP tune, Ive had Wait4Me on a previous vehicle, Hypertec, Flashpaq and by far I love the BBP tune

 

JMHO: if your budget is that tight right now, just get a tune. A tune alone will give you much more than shorties and no tune, and you will need a tune for longtubes to realize any benefit, so you'll spend that money eventually anyway. You can always have your tune updated once you longtube it (if you still feel the need after you feel the improvement the tune will offer).

 

^^ What he said!

 

I still have the stock manifolds and they are 1 5/8" inside diameter just like the JBA shorties I had.

 

On my 2007 Avalanche with the 5.3 I noticed the engine did rev faster and passenger compartment exhaust rumble was a tad louder. I had Gibson shorty's. It is also worth noting that an exhaust flange weld broke.

I have to say that the referenced header article gives an advantage to the long-tube headers in that the exhaust system tested with the headers is an all new dual exhaust system, whereas the shorties have the single muffler/pipe exhaust system. So, the objectivity is not exactly square.