I devised this method of modifying my 1g compressor bypass valve (or BOV as most people call it) to hold more boost pressure without crushing. Some may think this is actually more destructive but I think there is less chance of destroying the valve and the changes you make are reversible to a certain extent.
The stock 1g BOV is designed to hold back around 12 psi of pressure. When you get to the point where you are capable of producing more than 12 psi, the stock BOV will eventually become a weak point. Crushing the top or using this alternative to add spacers will enable the valve to hold more pressure.
Tools needed: dremel type tool with cutting discs, wrench, vacuum pump with guage.
Materials needed: 2” Quick clamp- 4322K153
http://www.mcmaster.com/ goes for about $10. 1.25” fender washers to be used as spacers-get from HD, Stainless Steel nut (optional to replace the large, heavy wing nut on the clamp).
1. Check the vacuum holding ability before you start by attaching a vacuum pump to the to nipple. You can see the valve start to retract at a certain point. Mine started to open at about 15 inHG.
2. Carefully score the stamped sheet metal cover around the center of the wide part. I played around with trying to uncrimp the edge but decided it wasn’t worth the time and effort. Try to cut just through the sheet metal although going a little deeper won’t hurt anything.
When you get it cut, the top will pop off.
3. Now is a good time to paint the top if you want.
4. Place a couple a washers inside the cap, put the spring back in it’s original location and clamp the thing together using the quick-clamp.
5. Test the vacuum holding ability again. The thick washers I used seemed to be good for a couple inHG each. If you try to get to 24 or over, your BOV may never open at all. The same recommendations as for crushing as far as maximum vacuum holding apply. From what I understand, vacuum holding ability should be equivalent to pressure holding ability in psi when installed.
6. Bolt it back into your car.
Ron Tew 
