The past few days I was ruling out a few items. Vacuum was near perfect and no boost leaks. I may/do have an exhaust leak but I wouldn't think it would DRASTICALLY change the idle.
The issue is with the HKS SSQ BOV mentioned above. It's a BOV usually used in turbo applications and the spring rating is above 6 PSI for sure. Just recently learned that the BPV needs to be partially open with a centrifugal supercharger. This translates to using a BPV with a 1-1.5PSI spring rating OR using an adjustable BOV that can get down to that area. Made sense. S.C. is constantly running (unlike a turbo) and excess pressure needs to go somewhere.
Replaced the BPV with the Bosh one and ran an idle volume relearn and then viola! Problem solved.
-------- BUT -----------
As some have said... what a $h|itty design. The MAFs are soooo close to the filters that the moment the fans kick on, fuel trims start changing because of the air flow and temp change. Did they test these kits in a vacuum 0 gravity facility?
As other have done... they did away with them or created a better shield. I used the one they provided (350z HR single intake pipe dual MAFs) and it does 0.
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