What is the correct proceedure for crushing a JDM MR DV? How do you know how far to crush it? What tools are needed to do the crushing properly? Has anyone verified an increase in boost holding on the JDM DV's after crushing?

Any help woud be appreciated. We used to crush the stock, fuel pressure regulators on Buick Grand Nationals before adjustable ones were available. We'd put a socket over the adapter and stick them in a bench vise.

 

The correctmethod for the 1G bov is to crush it until it takes about 19"hg (using a mightyvac or similar) to just crack the valve off the seat. Going to 20" will typically make the valve fluttery. Of course this will vary somewhat with the level of vacuum your cams give you, so the best bet is still to take it one step at a time. The MR valve should be pretty stiff already so I would go in 2" increments at the most. 1" if you can tolerate the slow pace.

The idea is to get maximum holding power without it running like ****. The numbers may differ in this application, but the procedure still applies. This mod is proven to increase the 1g BOV's capacity, but I have no personal experience with the EVO valve.

 

Put it in a vice and crush it uniformly without going so far that the nipple gets bent.