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The intake plenum is bifurcated, where the AOS ducting attaches to it, hence the two hoses (one on each side of the bifurcated duct).

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Makes sense. But why is there another 4" bellowed tube running parallel to the one that receives the AOS ducting? That's what I don't understand.
 

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Not totally enjoyable to me as the rear tires were completely useless. He needed 2 more inches of rubber patch to control the wheel spin in second and third gear. Maybe be great as a garage queen, but really on the open road, especially with twisty curves, not adequate at all. May car is planted with large RE71R's from last years auto cross that I am using up. Kind of noisy though. I got some rubber softener (Pro blend Premium Hot Lap) to put some life back into the tires as a test. They have more than 50% left across their face even with my camber.
If that adds more grip to the old tires, I will coat my Hoosier A7's with it as they rest in their air tight bags, ready to go this summer.
2" might not help; what size tires are they ?
My Grand Sport has 285F 335R PS4s which 5 sizes larger than the tires I had on the Spyder 255/285 with stock being 235/265 so that's a total of 7 sizes bigger and it will still easily light the tires up with only 460 hp 465 lbs. Problem being there aren't RE71R that big. May have to go to Toyo R888R's. But will probably just live with stock tires because the C8 uses different sizes and there's only 1 set of wheels for it on TireRack. Hopefully by the time I get my C8 they will more wheels to choose from. Also with the tires that are available I need 19" for the rear to get tires big enough. The C8 is a larger bolt pattern than the C7.
Let me know if the rubber softener works.
 

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Been noticing some funky electrical issues with dash lights while driving at night and slow cranking in the mornings. Had the battery tested and it was fine, so after a fair amount of fiddling I managed to wiggle the alternator out. Bearings felt fine, but the sniff test smelled like something was a bit cooked.

Took it into a FLAPS and it tested bad. New alternator ordered, should be in today. '07 Cayman with 106k. Not too bad considering how isolated the alternator is and how little cooling it actually receives. The one in my '86 944 is original to the car and has a dedicated cooling duct to pull cool air from the front of the car.
 

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Makes sense. But why is there another 4" bellowed tube running parallel to the one that receives the AOS ducting? That's what I don't understand.
The best I can add is since Porsche uses an expansion type intake manifold the added ~4" tube behind the main plenum tube may provide for bank balance and may add even lower intake temperature. This video explains the Porsche manifold idea well.
Porsche manifold explained
 

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The best I can add is since Porsche uses an expansion type intake manifold the added ~4" tube behind the main plenum tube may provide for bank balance and may add even lower intake temperature. This video explains the Porsche manifold idea well.
Porsche manifold explained
Interesting video, though the fellow claims that that intake system was introduced in 2008. My Cayman is a 2007 however, and, additionally, it isn't turbo'ed. Looking up the part on PET2 shows that Porsche calls it a "resonance tube." I assume then that the induction system on this car is a tuned system using a separate chamber rather different runner lengths.

Ran a search on "resonance intake manifold" and came up with these useful links:
Details on how does the OEM Plenum work?
 

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Waxed the starboard side rims..
 

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Picts please?

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The second billowed line from the AOS is a vacuum line that goes to the drivers side head to evacuate the head of frothy oil vapors. Need a picture to confirm.
 

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Been noticing some funky electrical issues with dash lights while driving at night and slow cranking in the mornings. Had the battery tested and it was fine, so after a fair amount of fiddling I managed to wiggle the alternator out. Bearings felt fine, but the sniff test smelled like something was a bit cooked.

Took it into a FLAPS and it tested bad. New alternator ordered, should be in today. '07 Cayman with 106k. Not too bad considering how isolated the alternator is and how little cooling it actually receives. The one in my '86 944 is original to the car and has a dedicated cooling duct to pull cool air from the front of the car.
Augie- What are the options that you ordered on your C8? I saw a big brake kit and a limited slip diff, but each was embedded in a package. No third peddle available. I am surprised as many Corvette customers like their manual shift. Did you get to take one for a ride?
 
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