Put on my Macs a couple days ago. Everything seemed to go on great but on the drive home, I noticed a few things. The exhaust really seems to pop frequently when I get on the throttle heavy.
Finally, when the car is cruising in 6th gear (around 55-65mph) with the cruise on, the car really seems to run rough. It's hard to explain what it is doing. The best description I can think of is every couple seconds it seems like the engine "jerks". Like the car just wants to stop running for a split second. This problem gets a little better when I put it in 5th when running under 75mph. It also seems to have this "jerking" problem when I really get on it.
It almost seems like the car isn't accelerating like it should when I gun it but it seems to be significantly faster than when it was stock.
The car idles better than it ever has before (no shaking at all, very smooth) and I don't hear anything that would indicate an exhaust leak (pinging, tinging, etc...). Is this all fairly normal stuff when you change headers before you get a tune? Will a tune fix all of this?
It should be noted that I changed my plugs and wires and took off all the coil packs and passenger side valve cover to get the headers in. I am all but certain that I put everything back together correctly. And it would be pretty obvious if I got my coil packs installed in the wrong order or if a spark plug wire wasn't hooked in wouldn't it?
Also, the mac y-pipe has spots for rear 02 sensors. I was able to retrieve one stock sensor and put it in, but the one on the drivers side was completed rusted in the stock y. I'm planning on getting some sort of plug to plug the hole but was wondering what size of plug to get.
Thanks for the help guys!

edit: oh yeah, I also installed my LS6 intake. Everything seemed to go pretty smooth with that as well. EGR and AIR have also been removed.

 

Check all the plugs wires and make sure they are on all the way i had a similar problem and 1 plug wires wasnt all the way on and the car would jerk when i was turning and it probebly would be a bad idea to double check every thing. And you can use an old spark plug to plug the hole im pretty sure they are the same size

 

Make sure you got everything plugged back after the swap, if you left a vacuum hose undone it can cause issues.

Like he said, double checking is always a free idea, therefor the best.

 

Having the same "jerking" problem right now. Did it end up being the o2 sensors or a cracked spark plug? Mine situation could also be either or, did a h/c swap, long story short, the shop did a shitty job putting it back together

 

The jerking thing. . . is it happening around 1500-2000 engine rpm? It sounds like 'lugging' which is hard on the engine.

 

Did I read this right or what? You're saying you have one rear 02 sensor hole completely open? Nothing plugging it? Thats a big exhaust leak close to the headers. I would start there and double/triple check everything. Also, it doesn't hurt to have another set of eyes go over it for you. Sometimes it will be right in front of you face.

 

My car was doing the same thing when I first bought it. So I just tore it all apart , so I can start fresh. lol (didn't know what they did to her) But when I was taking it apart, I noticed vacuum lines where falling apart, and they had the rear 02's in where the front 02's should have gone and 02 simms on the front 02's. lol (they really didn't know what they were doing) LT at that. Plus there were really crappy weld jobs on the exhuast, right after the LTs, leaks everywhere. One more thing, I had two plugs that were cracked and were arching off the head.

my .02

 

maybe the computer is freakin out cause of the changes and needs to relearn or something? some weird things happen with different cars sometimes.

 

Wow didn't notice that this got bumped back up after almost a year. What it ended up being was a plug wire that wasn't on all the way. It was that farthest back one on the passenger side. I just ended up replacing all of the plug wires. Not a big fan of those MSD ones just because they don't "click" when they are seated all the way and it is somewhat difficult to tell when they are on right. After that, the car ran like a top!