Here's a mod to improve the stock bov pressure holding capability. This mod is similar to the 1G BOV crush mod. Unlike the 1G BOV , the Evo's BOV is plastic therefor we cannot use the crush method. Instead, we will SCREW it! Well, here's how.
(1) get 2 - 3 fine thread screw shown in pic.

(2) Drill one hole at a time on the top of the BOV. The holes must be drill on the outer top of the BOV. you want to drill starting from where the spring coil ends. You can locate the spring by simply puting a magnet on the top of the BOV.

(3) After you drill the hole, you will see the metal spring under the plastic that you've just drilled. 1 or 2 screw should be enough. If you failed to locate the spring on the first attempt, just simply close the hole with a screw. and then try again.

(4) The drill bit that you use should be slightly smaller than the screw you have. This way the screw will go in snug.

(5) After you have finished with the mod, replace the BOV and go for a test! Tightening the screw too tight will create the stalling problem associated with aftermarket BOV. Good Luck guys!!

You Have yourself an adjustable stock BOV now!

 

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