I just purchased a used ZZP shorty header from Denny! Thanks man! Well anyways just installed it. Everything went smooth untill I went to bolt my stock downpipe back onto the new header. It didn't line up perfect but pretty close. Well now the stock converter is sitting on the sway bar. Obviously that is a problem.......When I shifted the converter off of the sway bar then the downpipe was sitting high up on the header outlet exposing probaly a 1/4 a inch. Any ideas? this is the first time I have ever installed a exhaust component.

 

short verson: a lot of times, you just have to play with exhaust stuff. my guess is that you moved something on the dp/cat back when you removed the stock one and now the mounts arn't sitting right

 

i would recommend disconnecting the dp from the exhaust, bolting it to the header FIRST, and getting it lined up there, and THEN re-connect it to the exhaust. the flex part of the stock dp is very hard to move, and you don't have the leverage when you're trying to bolt it to the header. it's worth a shot.

 

did you already tighten down the header like fully before you went to put the dp on? bc if you tightened everything before it all fit thats where your problem may be. let me know

 

yes i tightened the header all the way down before bolting the downpipe back up. should I unbolt the downpipe from the cat back like stated above?

thanks a lot man worth a try indeed

 

no prob. good luck. if that doesn't work, then it's just poor fitment and you'll have to try to ghetto rig it somewho

 

yeah you could do that. i would even try both; meaning loosent the bolts on the header a bit so you have some play, connect the dp that you unbolted from the catback, put the catback and dp back on only finger tight, then fully tighten the header down and then finally fully tighten the bolts connected the dp to the catback.

 

well i bolted everything back up again...it still isnt right! the converter is stll on the sway bar. it is like the header isnt down far enough and it is drawing the downpipe up further. I looked at the rubber hanger fo the catback and you can tell that it is ll pulled forward about a inch. Nothing I do is helping.

 

At this point I say midas it and bite the bullet.

 

when you set the header next to your old exhaust manifold is it noticeably shorter?

 

thats there shorty header to a T...


i had the same issue so im pretty sure your install was fine its the header.... i had to cut 2" out of the DP and that fixed everything, or did i add 2" dont remember i have a catless DP now well what ever it was im sure you can tell by lookin if it needs some or needs less!


what DP do you have? i was running the ZZP shorty header and 3" catted DP


i have had just about every problem ZZP has to offer...

 

he's got the stock down pipe...

 

it is the stock downpipe. yes it is act like the downpipe needs to be a little longer since when you bolt the down pipe up to the header it is drawing the rest of the exhaust forward

 

i would say you're going to have to either fab up a downpipe, or get rid of the header. keep in mind that the exhaust moves a decent amount, so even barely clearing it is not enough. once you hit the gas the engine moves a pretty good amount, and will end up hitting the bar anyways.

i wonder if that's why he sold the header?

also, aftermarket cats are a good amount smaller than the stock cat. so that's another option, either look into a downpipe or at least a smaller hi-flo cat. that may give you the clearance you need. the stock cat is like a 5 gallon water jug

 

Well I hope that a mod on this site wouldn't sell me a header that was supposed to "fit perfect" and it doesnt...but I'm sure I can make it work. Yea I really need a downpipe but I am kinda broke. If I just cut the cat out and run a straight pipe I will have to find someone with HPtuners huh?

 

or a code scanner can shut the code off. it's probably a much cheaper alternative. if it comes back, just delete it again. the light isn't anything other than annoying to look at though.

 

it will not affect the performance of the car? in a bad way? I thought I heard it will make the car run rich?

 

maybe someone that has done before and after logs can answer that better than i can.

i can say that on both my cobalts i've swapped out the downpipes, and the p0420 code is fairly common. i never noticed any driveability issues on either car, and never got a rich code.

someone correct me if i'm wrong, but i think the 2nd 02 sensor's main function is to determine if the cat is working properly. the code it throws when messing with the downpipe is because the sensor is reading more air than it's programmed for, so it thinks the cat is failing. it may also have something to do with ltft, really not sure about that part though. best bet is to let someone with scanning/tuning experience chime in.

 

well lets hope someone does soon