Wow I have an IPd Hd CBV kit just coz my original CBV diaphram was old and fatigued and it was cheep to throw on when purschasing other things. Anyway i have always run the stand spring 8lbs i changed it last night to the 10lbs spring (BLUE) and WOW what a difference it made hello BOOST and boost control the only issue I currently see is earlier boost onset and holding it stronger and longer as expected buy changeing the spring. as I have stock rods but is Tuned by Aaron @ VAST. ( I Highly recommend him) so I actively concious of that but yer wow what a fun car to drive and a volvo lol. the car runs around 18PSI TD04 18T