Good to know thanks! That car is a track only car and I did the kooks headers also (with jet hot 2K coating) to also save on weight.

Did you change the cats also? Changing to high flow cats definitely makes it way louder! Tempted to go back to stock cats and leave the headers and get the track exhaust as that will save some weight and the stock cats are not tons heavier. And then I won’t get a CEL either. But I could get a tune now to fix that. But that is more $$$.

 

Stock cats. Don't want the car any louder, and don't want to deal with CEL or aftermarket tunes and risk warranty being voided on the drivetrain if something needs repair, and gives the dealer an out to deny warranty repairs. They pull that crap all the time. Not giving them any wiggle room.
Car is fast enough, not worried about making more power, just making it handle better.

 

Good discussion on the exhaust! I often shun from it since there are noise limits at the tracks, and I always fear engine compartment temperatures since OEM exhaust is shielded very well, yet most-all aftermarket exhaust aren't. Perhaps it might be something to explore once I feel settled with suspension, etc : )

 

I'm the same, but if you look at the design of the Corsa, it mimics the OE straight through design, so it is not close to any other components, and the car has lots of heat shielding in the exhaust area already. Couple that with the underbody air-ducts we use to scoop cool air into the engine compartment, and removing the exhaust muffler allows for higher air flow out of the back bumper mesh for cooling to extract any additional heat back there. I've had zero issues with additional heat on anything chassis related under very hard track use.

There are many other silly, overly complicated, and non-heat shielded aftermarket units out there. I agree, I wouldn't bother with any of them either, as they are just bling that make things worse compared to OE. I spent alot of time trying to find the most sensible, track exhaust to shed weight and add a little more sound. The Corsa fits the bill. I think you would be really pleased with the handling and sound increases it offers.

 

Looks close...

 

Thanks for the insights. 30+ lb of savings is huge, especially on a car with 61% of weight on the rear axle...

That's it!!!! "Strainer" - I kept searching for drainer with no luck, but now I know what it's called. Thank you very much!

 

Yeah and the cats make a massive difference in noise. Tempted to swap mine back.

 

Ding ding! Yes. Heat is an issue. I just lost the rear camera. again. And I did jet hot coating on the headers. Not sure if it was the exhaust or the rear diffuser I installed as it was fine until I did the diffuser. It is the RSC one which closes off the entire bottom and I think it doesn’t get enough airflow. So I plan to swap that back to stock also ….

 

The car is finished! I just need to get it aligned, now.

(Done | In progress | Pending)

• New tires mounted on new wheels
• Studs installed for UCAs
• UCAs replaced
• Rear LCAs replaced
• Coilovers installed
• Corner-weight balancing
• Adjustable endlinks installed
• Alignment (scheduled THU 4/2)

Corner weight balancing numbers (FL, FR, RR, RL):

• Weight (in lb)
  • 208.7 lb ballast with ~75% fuel.
  • 3783 lbs total.
  • 761, 745, 1122, 1155
  • Corner weight balance: 49.8%.
• Height (in mm)
  • Goal: 100 front, 124 rear.
  • 102+, 100+, 126+, 124+.
• Starting Preload (in mm):
  • Measured from the bottom of shock where the perch threads start to where the spring starts.
  • 100, 100, 174, 174
• Number of perch turns from starting preload
  • +3.5, +0.5, +2, +1

I installed the canisters into these locations.


JJ recommended using aluminum sheets with grease in between them to act as an alignment plate to let the suspension settle during corner weight balancing. I eventually decided against using it, since I am also using 12" cribs, and it could get very dangerous if it fell out of those cribs due to these sheets!


This is the setup I've used.


Besides, there's low friction between the scale and the cribs, so they let the suspension settle anyway, as you can see here.


I threw threw the towel at 49.8%. The shocks started with 100mm preload for the fronts (measured from where the perch thread starts to where the spring starts), and 174mm for rears. I was able to hit these numbers after turning perches listed amount of times.


The rear endlinks had to be extended quite a bit. I am thinking about clocking the rear sway bar's neutral position a bt to reduce its length. Anyway, I did not have time to do so this time.


The front endlinks had to be at their shortest, and that did not clear the shocks. I had to switch back to OEM endlinks with a bit of preload.Since left to right was very close in height, I could possibly clock the sway bar and get away with most of the preload as well.


Finsihed; yay!!


R8 315/30/18


R8 345/35/18

 

Yeah it's the diffuser. It needs to have ducts sending air into the rear exhaust compartment. If you look at cars like 992 GT3/RS cars, the factory rear diffusers have multiple naca air ducts built into them to cool the exhaust area and increase air-flow in there.

 

Not to burst your bubble, but I don't see how you could get accurate setup data with your equipment. Allowing the suspension to slide out and settle after you lift it each time is critical. SLA suspension moves on an arc and when lowered the car sits high until you roll it and it will naturally settle out. Sticky tires exacerbate the problem. Best way to do all this is with hub stands that have roller bearings. Or, just pay a good shop that has all the stuff.

 

I lose my camera intermittently too. Milltek HFCs, OEM exhaust and diffuser.

 

There are 2 important pieces to the puzzle: the cribs for free play, and level ground.

• I use the cribs for 2 reasons: let the car stay clear of the lift arms during the measurements, and let the suspension easily settle (you can visibly see toe and camber settle).
• I have previously balanced the garage ground to be flat by stacking plywood at various heights until it was flat on the bubble measure left to right and front to back.

The cribs are not fixed on the scales by any means, and they freely slide on them. Every time I lower the car, I first rock the car forward and rearward, and then I jump on both driver and passenger side of the car, and let the suspension settle. This makes the suspension settle and you can visibly see the tires move outwards on the sides after this. In fact I end up having to move the cribs back, centered on the scales after a few such measuring, since they move so much.

I verified the results of this method with what we got at a professional alignment shop before on my C7 Z06, and the results were almost identical. I paid $50 for using weight scales on their alignment rack, and the results were very comparable.

So it works, but all that jumping and humping takes a lot of time and gets tiring. I thought about adding two aluminum sheets with grease inside to replicate rollers to make it easier, but decided otherwise since the car is not on the ground, and feared the whole car could slide away.

 

Endlink debacle:
Hmm, I think I'll revisit the endlinks tonight. The front endlinks are supposed to be 80 mm long, and the rears are supposed to be 192 mm. From there, you're supposed to do minimal adjustments in height to take up the difference in heights from left to rear, and that's it. In my case, the fronts needed to be shorter than even the shortest setting, and I think the rears extended beyond how long they're supposed to. I think this is an issue with where the sway bars are clocked at.

In my opinion, the only good way to solve this is by loosening or opening up the sway bar mounts, greasing it up a bit for it to start having free play, clock it to hit the spec height for the endlinks. This should be very easy to do at the rear, but not really sure about the fronts since the mounts up front are hard to reach. Anyway, I want to do this for the rears for sure, and go from there..

The sway bars didn't seem to have lube by the mounts, or at least I did not see it. I wonder why GM decided to go this way, since it induces unnecessary preload to the system. The mount bushing felt a bit slippery; perhaps that was the idea. You can't really install a grease zerg, either, since the mounts are not circular, and are not meant to rotate inside the mount. For this reason, I'm thiking about opening up the mount, and greasing up the bar directly with NLGI #2. If you know of a reason on why I'm not supposed to do this, would love to hear it! : )

On a side note, after clocking, the front adjustable endlinks might start clearing the shocks as well; we shall see.

 

Dude, you should just get some hub stands. I can do all that stuff with the suspension loaded.

 

https://www.corvetteforum.com/forums...ub-stands.html

 

Those stands look great!

Endlink clocking method
I think I found a good solution to this. I took out the endlinks that were load-free on the cribs, and they were 2 mm apart from each other, which is about same as the height difference from side to side as well. Due to the way suspension compresses, the lower side has the longer endlink. The problem is they were around 205 mm long, way longer than 192 mm of the spec. I set them to 192 mm and 194 mm respectively, reinstalled, and then loosened the sway bar mounts to let the sway bar clock with the weight of the car. Once the car is on the ground, you should then torque the mounts while the car's weight is on them. This way, they are clocked right, and the endlinks are also in spec lengths. No wonder, GM also asks those mounts to be tightened on the ground as well. Yay!


I initially removed the sway bars to see if I can clock them, but it was clearly not possible.


This bushing is not meant to be opened up or moved around; it doesn't budge. That said, those big gaps on each side give you the clue on how it works. When the mount is loose, it allows the sway bar to clock and settle. Once you tighten the mounts, those gaps are compressed, and the sway bar no longer wants to play along.


So, just leave the mounts a bit loose, and only tighten them when the car is on the ground to achieve the right angles and no unnecessary load.

Found another problem while going over things: Well, it turns out that I forgot to tighten the left side LCA's conical joint to the hub! I tightened it now, but I wonder if it messed up my corner weights. I am thinking it shouldn't, since it will impact alignment more than anything, and height is mostly determined by the shocks that are connected to the hub (and even endlinks were disconnected), but not completely sure. I don't want to disconnect endlinks again, put the car on cribs and scale, add 208 lbs of ballast by carrying junk into the driver's seat, etc. just for a 'quick' verification : (


Oops, it turns out I forgot to tighten this : ( I am thinking it would impact alignment more than anything since LCA maniuplates hub angles, but not completely sure...


One final issue I've seen was the wheel weights hitting this part of the UCA (see the tiny witness mark). I moved the weights further into the wheel, and also grinded that area a tiny bit to create more clearance. These wheels are 12.75" wide, wider than any other 18" wheels I've used, and little issues like that is a bit expected I suppose.

The alignment is scheduled to be done on THU morning. Now I need to decide to just leave it alone or redo all the weight measurements; hmm : )

 

Heights, JRI settings

Now that we've covered weights, we can talk a bit about heights and suspension settings.

Z06 Stock: 358 mm F, 385 / 383 mm R. 26 mm rake.
JRI Target: 348 mm FR, 372 mm R (FL/FR/RR/RL)

• @9/27/25 Actual: 348/347/372/370
• @4/1/2026 - ~25mm rake.
  • 102+, 100+, 126+, 124+. 350/348/374/372 on cribs w/ballast
  • 352/350/376/375 on the ground w/ballast
    • There's usually a few mm difference measuring on the ground vs. on the crib due to tires being massive and not fitting the cribs fully. As long as they're consistent among each other, it's not an issue, and they are all consistent.

JRI shocks' adjustment range:

• HSC: 24 clicks, HSR: 12 clicks
• LSC: 30 clicks, LSR: 30 clicks

Default settings:

• FRONT LEFT
  • HSC+10, HSR+8
  • LSC-8, LSR-7
    
• FRONT RIGHT
  • HSC+9, HSR+8
  • LSC-8, LSR-8
    
• REAR LEFT
  • HSC+6, HSR+7
  • LSC-10, LSR-8
    
• REAR RIGHT
  • HSC+6, HSR+7
  • LSC-10, LSR-8

Observation: Looks like I have at least 7-8 more clicks available to max, except on HSR, which is only 4 clicks away from max on fronts, and 5 clicks on rears. Here's hoping these are very meaningful clicks : )

Rake
Below are rake of some of the setups (adding onto suspension rake).

Hoosier R7 / R8
295/30/18 25.3”
315/30/18 25.6” 27.6 lb / 25.6 lb
345/35/18 26.8“ 31.1 lb / 29.1 lb

Hankook F200
300/680/18 675 mm 26.6” 26.5 lb
320/710/18 706 mm 27.8” 29.6 lb

• OEM tires 16.51 mm, suspension 26 mm. Total: 42.5 mm.
• Current rake: ~25 mm.
  • R7/8 18” 315 / 345 - 15.2 mm, Total 40 mm. --> My current optimal setup, which I'll use for alignment, too.
  • F200 18” 300 / 320 - 15.5 mm, Total: 40.5 mm.
  • R7/8 18” 295 / 345 - 19 mm, Total 44 mm.
  • R7/8 19” 295 / 345 - 8.9 mm, Total: 34 mm.
  • Toyo R 18” 295 / 345 - 31.75 mm, Total 56.75 mm
  • Toyo R 18” 305 / 345 - 19 mm, Total 44 mm

In other news, I sourced the recall part for fire risk for $5 + shipping, and replaced it in about 30-45 seconds. I then got it reimbursed by GM, not to get my money back but so that there'd be proof in their records that I sourced the part. That said, even though I've also provided them pics of my install, they reimbursed me, but are still not marking the recall as complete. grrr.


The new one has a narrower opening for the fuel kneck, and seems to hug it tightly around to avoid leaks.

 

What is the part number for that new neck? On another note, would you have tried the DSC controller on the stock mag ride if it were available, before going to coil-overs?

 

It's 86371991 per this article:
https://gmauthority.com/blog/2025/10...s-will-fix-it/

And yes I'd absolutely give DSC controller a shot if it were available. It'd be a lot less messy and much easier to return to stock when it's time to sell the car. Usually, OEM shocks are adequate when calibrated for your use case as long as the car is not heavily modified (e.g. much more aggressive aero).