I've heard this term tossed around and am not too sure what it particularly means. Can somebody enlighten me on this subject?

 

What it means, is that you are placing shims (washers) between the oil pump relief valve spring and the bolt that holds the relief valve assembly in place. In return, this puts more pressure on the spring causing the relief valve to open at a higher psi.

 

Here is a thread I made a month or so ago, still working very well today.

https://honda-tech.com/zerothread?id=1396607

 

Thanks for the information guys.