yes. that is what i meant by "catted", and not catted. still didn't answer my question.

 

I don't know about the diablo but you will need to tune the rear o2's out. Fuel will need to be adjusted across the board likely.

 

ill wait to do the install until i know i can get it in to be tuned. im assuming it will run, but poorly, until it is tuned properly ?

 

It'll run fine, just definitely not as good as it could. If you use the rear O2's, you'll probably get a catalytic converter efficiency code since those resonators ("cats") have only small perforations inside them and might not show enough difference in flow between front and rear O2's. If you don't use any rear O2's, then you'll surely get a code until they are turned off in your tune. You could actually have the rear O2's turned off beforehand as it won't affect driveability. The rear O2's just make sure that the "cats" (real or otherwise) are functioning....or not.

Some claim they you don't "need" to be re-tuned with longtubes, but you dsefinitely "should" because not doing so is "half-assing it" IMHO. Anything that changes the intake/exhaust flow (CAI, camshaft, headers, heads, etc...) should be tuned for, so you'll get the most bang for your bucks...A cam swap in your car or truck will "run" and not "need" a tune to do so (usually), but obviously you "need" a tune to maximize the efforts. Headers are no different, just not as drastic of a tune change.

p.s. I'd wager there has been at least a hundred sets of these headers sold due to this thread and if I couldn't get a free set, or even a "deal"...then I'd all but guarantee that nobody else will.

 

so here's a bit of real-world info for y'all:

as most of ya know, i've had these on since the end of january (didn't drive at all in march, so take a month off my time). i'm in the process of having a BlackBear datalog tune done & should have my new computer within a couple days. until last week, the only driving i'd done was around town/base at 1/2 throttle or less. i never had any tune or drivability issues running on my old tune. surprisingly, the only O2 issue i ever had was that in the middle of my datalogging last week, my Bank 2 Sensor 1 (front passenger side) started to die. (165k mi on the original O2s... i reckon that's pretty good). i never even got a CEL for the rear O2s at all - they're in/plugged up but obviously are behind resonators instead of cats. i replaced the two upstreams with some corvette rears & the issue is gone. other than that, i ain't had any CELs except on the way home this weekend, i got that P0102 again - it always comes on when i spend any significant amount of time driving 85mph+... still ain't figured that one out.

as for untuned mileage: i went from 16 in town to a little over 17. before, my highway mileage was about 18ish. on the drive home this weekend (450+ interstate miles), i got about 17.5 driving anywhere between 70-85 with a couple quick 100 pulls because i was getting really bored @ 3am. average was about 75. what really threw me for a loop was the trip back... i drove 85% of the way between 60 & 70, usually hanging at 65. no joke - i got 21.4mpg! it really freaked me out when i noticed i was using less gas. i saw the needle sitting on the 1/2 mark & remembered that i'm used to seeing the trip counter somewhere close to 225ish & when it was almost at 310, i thought my needle stuck or quit working. i hit the clutch & restarted the motor right there cruising down the interstate to make sure it wasn't a fluke. needle dropped & came back to 1/2!!

i can't wait to see what the actual tune does for me!

 

http://cgi.ebay.com/ebaymotors/CHEVY...Q5fAccessories

found these today on ebay for $287 shipped

 

No it doesn't, as far as I went with my LT's the exhaust shop had to fab me up a new one using my old Y. Or I could have bought a new one from magnaflow. The LT's are too long for the stock Y; if your running cats you will need this. If you want to run straight pipe then it might work dude.

 

Ordered mine today from DNA Motoring directly,called them up, 290 shipped.

 

Evidently one of us seems to be reading this question wrong...

The Ebay header supplied Y pipe does indeed end up in the exact same position/location as the stock Y pipe does. In other words, the Ebay setup will bolt directly to the stock, or any stock style exhaust system on vehicles that the headers are intended/designed for.

A stock, catted Y pipe will NOT bolt directly to these headers, but I don't believe that was the actual question...although I am old and accused of being half senile.

 

I have an 03 z71 and am thinking of getting these headers everyone seems to like them alot now the problem is what i have been hearing about the "hit or miss" situation i really would rather not have to take a hammer/crowbar and bend the heck out of them so does anyone know if anybody has had luck with 03 and up header installation

and can someone post the link to the ebay page for me? thanks