OEM BPV works fine until you go larger turbo. Both my BPV's are using the original springs still. I have the lighter spring for the GFB, but have not needed it yet. Will need it for the 68HTA.
To remove the bumper skin you must remove a bunch of popits. Hard to explain in words. The 4 clips for the grill need to be released. The 4 popits around the grill need to be removed. 1 popit in each front fender well need to be removed (behind tire). 6 popits under the front of the car need to be removed. 1 popit hidden in the fender well lining right at the edge of the fender and bumber skin need to be removed (both sides). Pull the edges out of the track (fenders) pull from the front. Once it is off, remove the fog light wires. Be careful the skin scratches easliy.
I think that is all of the popits. Off the top of my head.