So I bought a 370z with a stage 1 GTM kit and Tial QRJ bypass valve. The fluttering drove me nuts at the start. I contacted Tial and we took a vacuum reading. The spring I had seemed like the correct spec, but they sent me 2 other springs (one stiffer and one looser) to try. Each other spring made it worse. After awhile I found a couple guys that have the same setup and both said it's normal for them.
I don't have any good videos of the fluttering, you can sort of hear it at the start of this video though. It's definitely annoying, but now that I know it's normal it doesn't bother me quite as bad.. wish I could do something to quiet it up, it's already recirculated to the intake
https://imgur.com/gallery/YabPywU
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