Beware of BPV snake oil.
 

As a noob here, may I politely offer something from my own experience, even though it might stir up a hornets nest? :)

The early failures of the Bosch 710A BPVs and a widespread lack of understanding about its function seem to have spawned a sizable aftermarket for alternatives. I too fell for the claims of piston type DV vendors. I got Forge, Bailey and other exotic stuff with different springs and plastic or aluminum pistons, and found them sluggish, exhibiting sticky or canting pistons. When the 710N BPVs came out, I ran them for several seasons of tracking on my car (27PSI) without failure.

Here’s why the Bosch 710N is my BPV of choice.

The 710Ns have a stronger diaphragm to avoid material fatigue under continued aggressive driving. High boost was never a factor because the 710N diaphragm always has near equal pressure on both sides. The graphic explains.


http://209.128.70.155/BPV Principle.jpg


Above all, the low inertia of the Bosch 710N makes it quick and responsive, retaining the part throttle modulation of the N249 which is impeded by piston BPVs. Besides, should the 710N ever fail, a new one is cheaper than a rebuild kit for most piston BPVs.

I have my flame suit on. :)