See my thread here: https://www.corvetteforum.com/forums...post1604432648
...which contains links to tools, PDF instruction documents, and everything else I used to complete the job and what I learned in the process. It's an easy DIY swap that can be done in your garage without ever lifting your car or taking the rear wheels off, just take your time and be patient more than anything else. I did the driver's side working solo on a Saturday afternoon then completed the passenger side the following Sunday morning.

I'll also add Corsa's instructions here as well as an additional resource since I don't believe I included them in the link above: https://cdn.shopify.com/s/files/1/18...f?v=1614884205

 

This is very helpful, thank you!

 

Another question as I am currently in the middle of the install. Almost done with passenger’s side.

Are you reusing the oem manifold gaskets and bolts?

 

No & no, aftermarket headers include the new necessary gaskets & hardware. I'm not sure what brand of gaskets ARH supplies (the ones they picture look pretty generic though), but I know aFe supplies new OEM GM gaskets. As info, Kooks/Corsa/Lingenfelter supply Cometic gaskets.

 

Finally got the install done and it was brutal! I've done a number of header installs over the years and this one did not go smoothly. I found the AR headers, 1 7/8 X 3in on ebay, a new, unused set and received the package within 2 days. As represented by the seller, the box was unopened, and the reason for sell was that he sold his C8.
Install:
I opted to remove the wheel on the passenger's side and the liner, which was not really necessary TBH. I completed that side by myself in about 6 hours working at my own pace and triple checked behind the work completed. Note, AR supplies a clamp for the coolant line that runs on the underside panel on the passenger's side by the oil fill reservoir. It's important to install this clamp with the header out as it is easier to access the bolt underneath the panel to use to bolt down the clamp that used to keep the coolant line at a safe distance from the header. I ended up installing it afterwards and it was a pita. I found it more comfortable working out of the trunk but man, it was hot! Funny thing is, I thought I was pretty flexible until later that evening, I had pain in my hands, scratches up/down my arms, bruised forearms, knees, abs and aches everywhere.

The fun started on the driver's side, which I thought would be the earlier of the two sides. Well, I removed the factory manifolds and accessories in about 2 hours. Note, I did not remove the tire and wheel liner on the driver's side. Now it was time to install the header. First snag was I crossed threaded the middle bolt. So I had to address this and second issues were the two most rear holes on the header did not line up and were a little off, even with the cat loose. After trying different ways to get this resolved..ie loosing the bolts after the cats, but to no avail. Man, I was at this for a few hours...breaks in between. I even reached out to a few members here who installed the ARHs. I called AR and it was recommended that I remove the cat from the car. I saw videos where some installers removed the rear bumper to remove the cats. I was not there mentally and decided to call it a day. Next day, I removed the airbox (first time...GM did a great job securing sensors to the box; good to have tab extractors). Then I had more access to the nuts that connect the cats to the exhaust, which has a flex pipe too. I used a pry bar to undue the connection and unbolted the hanger that holds the cat (be prepared to hold the cat, as mine dropped a short distance before I caught it). The recommendation from AR worked! I installed the header by starting the bolt in the rear most position then the middle followed by the first. Finally installed bolts in the second and fourth positions. Left them loose pending the install of the cat but I decided to quit for the day.

This morning, got up early with my game face on! Installed cat and had the challenge of setting the exhaust back into the cat. That flex pipe can be tricky, but I stayed at it and finally the cat slipped in place using the pry bar and muscle on the left side (my left hand). I secured the hanger on the cat and moved back to the header bolts. Secured the header bolts, then the cats and finally the exhaust. Reinstalled the O2 sensor (used antiseize), the airbox and left the rear panel off until after making all connections and starting the car. Started car (not that much louder) and let it run for 15 minutes to burn of the coating while I checked for any issues. Drove the car around the neighborhood and no codes appeared...yes! I will check header bolts again after another short drive. After that, I will get on it a few times. I did not notice any more cabin noise as of yet. It is a little louder outside the car and make get louder as I put miles on the new set up. If you are planning to do this install, it really helps to have a second person, a variety of tools and you must be very patient. I will provide an update soon and will definitely see what gains noticed at the track. Before I forget, thanks to those who provided feedback and ARH!

 

I had exactly the same problem bolting the AR headers to the cat. It looked like the header flange was welded several degrees out of position though AR claimed that this was not the case and said that I should rotate the cat to align. This did not make sense as the other side bolted up without issue and I was not about to take any more of the car apart. So, I simply enlarged the header flange bolt holes and used washers for a nice bolted connection.

Bill

 

Bill, when did you buy your headers and what side did you have issues with? I started to do the same thing you did but wanted to try the cat removal method first, which it worked out!

 

Uhh wow... My aFe headers fit perfectly without issue; easy solo DIY. Sounds like ARH's jig is off. Airbox nor cats had to be removed or even loosened.

 

cat removal method? Could I get some info on this please sir? Thanks

 

I believe AR had a few revisions on their headers and mine were produced in late 2021. As mentioned, the passenger's side went right on. It would be important to mention the possibility of removing the driver's side cat in the instructions for those specific production runs. This also requires loosening the exhaust so you can remove the driver's side cat.

 

I had the opportunity to drive the car more today after checking down the bolts. All were secured except one (got a half turn or so). Cold start was louder this morning. On the interstate, I conducted a few half-throttle pulls and the car feels STRONG and very light at the throttle. Not a lot of effort to get it moving. It will be interesting to see the gains at the track. I posted a 2.80 0-60 with AC on and 38 psi in rears. The car really feels good! I will post track results soon.

 

01Defense - To answer your question, I bought the headers directly from AR on 7/4/21. Only the driver side bolt holes had to be enlarged. Since the install, all is working well without any leaks. In addition to the headers, I also have the Halltech air cleaner, Soler ported 91mm TB, ported intake, Borla Type S exhaust (I never had to do a valve relearn with the Borla)- with all of these mods, I have never had a CEL. My car is a 2021 Z51 with NPP, mag ride, 3LT coupe. My next mod will be a set of CNC heads.

Bill

 

So, you may have headers that were part of the earlier production run like mine. Wow, you have the mods that I will be installing soon, particularly a ported intake. I already for the PTB and Attack Blue filter element. I will see what gains the headers net first then move to install the ported intake. Btw, no cel here and I am close to 100 miles on the car following the header install. The headers really woke up the car! My car is a 23 Z51 with perf. exh., mag ride and a 3LT coupe. Beautiful cars!

 

Do you have high-flow cats?

 

I kept the stock cats as the power gains from a cat change were not worth it to me as well as the sound from the Borla S was perfect for me.

Bill

 

Makes sense, exactly why I went with the GM-version Borla exhaust since I already have headers + cats. I was afraid the Borla S would be excessive.

 

So, I was able to make it to the track late yesterday and lets say a little disappointed at track result, albeit the DA was terrible compared to a previous trip to the same track. On 2/19/23, stock I ran 11.43 there with a 1.68 60FT at 119.87 trap (7.36 1/8 @ 96.15). The DA was 904. I then added a PTB and AB Filter. On 3/29/23, went to a different track and went 11.30 with a 1.72 60FT at 120.97 trap (7.25 1/8 @ 95.60). The DA was 253. On yesterday 4/14/23, went back to same track where I made the stock pass, with addition of AR headers and my first pass, ran an 11.29 with a 1.67 60FT at 120.26 trap (7.23 1/8 @ 96.77). The DA was 1740. Second pass, ran an 11.31 with a 1.67 60FT at 119.81 (7.24 1/8 @ 96.69). DA was 1532. I made these two passes before someone OILED the track one car before I was to make another pass with the car having cooled down for about an hour and 1/2, SMH!!! (waited 2.5 hours while they attempted to clean but left at 11p; DA dropped about 200ft).

It's weird as I thought I would see higher trap speeds despite the unfavorable DA. Headers are working down low, but I was expecting to see at least 2mph gain at the top end. Note, I got to the track late and there were a number of cars there, so I did not get to let the car sit for more than 20 minutes until later as noted above. The lines was some what long so I was starting and stopping the car....heat!! Other racers were noting they loss ET and trap speed as well. So, I will install the ported intake manifold soon and wait for some good air while I put some miles on the car. Just wanted to follow up with some feedback

 

If I'm reading it correctly you ran the same e.t. and mph, only adding headers, and the DA difference was +1487 and hot lapping. I would call that a gain of more than a car length in similar air. Looking forward to your progress !!

 

I agree with you Snowblind. I had the same exact gain.

 

Yes, not much of a cool down until the end…track issue negated any run following that cool down. I do believe with a comparable DA as the previous runs, the car will run at least 2 tenths quicker. Btw, how are you all performing your burn outs?