Just installed a Forge BPV (stock type) that I purchased through Bad News Racing last night. I did use the yellow spring instead of the green spring since I have the GMTU installed.

I will say the boost is more consistant now than with the stocker. Boost at WOT doesn't spike as hard either during the shift.

Previous issues I was fighting was the following...

Boost surging under load between 5 & 10 psi at cruising speeds when accelerating and the ocasional overboost code.

 

Awesome glad to hear it. The Forge BPV was my very first upgrade. I have the GMTU with the green spring, I may swap it for the yellow one because I have noticed boost goes down sometimes like it doesn't maintain boost like it should. I hope the yellow spring will help

 

I debated on installing the yellow spring for a few minutes while waiting for the engine to cool off before diving into the engine bay. Glad I did. I think the green spring is better suited for bone stock applications.

 

Cool I'll try it out then, thanks

 

Wow. It does make a difference. Yellow spring for sure. way better than the green.

 

Today I did a hard accel from about 35 mpg. After the trans downshifted, boost was holding around 12-13 psi instead of fluctuating between 5 & 10 psi.

It's so nice.

 

Yup big time, I have the GM tune, mine would go from 22 to 15 then back up, now Im at a constant 21 22. You can really feel the pull, amazing what a small little spring can do

 

Well, had a overboost code pop up yesterday at the track. Going to have to check the GMTU connections again. I'm hoping it's something simple. If not, going to get it re-tuned.

 

Forge makes 4 springs for the valve, the more boost you have the more spring you need to hold it closed. Mine hits 26 and the yellow spring leaks a touch, but the red one holds it fine. Each spring is 25% stiffer.....

 

I have the GM tune mostly boost between 20 and 22. The green spring was too weak, psi would go up and down a lot. After I swapped out for the yellow spring everything was more constant. No codes or anything odd yet. Going on a few weeks now