Agreed. After I adjusted the tables to make sure the air didn't come in too fast down low, I got rid of the flutter because it wasn't making too much boost when there wasn't enough vacuum to open against the stronger spring. I may still drop the green one back in. I originally said the green one was fine because the strength of the spring is relative to the vacuum the engine generates. (the vacuum of a 2L 4cyl) The boost holds the valve closed, it is the vacuum on the other side of the plate that opens the valve.

 

Ive read numerous times anything over 20psi should use the yellow.

 

At the Forge site they don't give psi for the spring kit fitting our BPV like they do for the other spring kit they sell. They say it is an increase by %. (% what? I dunno) It looks like they are saying that relative to the green, yellow is twice as stiff, blue is 3 times stiffer, and red is 4 times stiffer. I still think green is fine for most of us even between 20 and 30psi.

 

Why do you want to go up to 26psi? I thought anything above ~24psi was out of the k04 efficiency range. Is that pressure needed to run meth?

 

you can run meth on any pressure. the trifecta tune goes to 27 psi and i hear a lot of people are happy with that. plus meth is a pain in the ass to tune for, i hear

 

I use the yellow spring on GMtune and have not had any problems.

 

Its a pain to tune. But I plan on running e85 sometime in the future

 

No pain other than the cams for it from ZZP. Had I those in my car, I could be tuned for it same day. While the torque curve may differ slightly, it is mostly about getting enough fuel to the engine when it needs it. E85 should be about a 20% increase in fuel vs air. It should work fine with the spring you are running now.

 

I'm GMTU and have had trouble holding boost on the freeway finally today I switched to the yellow spring. So far so good I'll try tomorrow nigh on the highway to see if it holds