Gentlemen, cutting the spring is a very bad idea!
The "issue" is a lack of bypass/return volume at the relief piston, and it only occurs when there is more volume than the valve can handle. (Think cold motor or very high rpm's)
Cutting the spring will lower the operating oil pressure, and it won't do a damn thing for the excessive pressure during cold starts, or high rpm pulls.
Just pull the oil fitler housing housing and do this job correctly. (Prove it, you don't have to remove the oil pump/front cover, just the oil fitler housing)
The info on the heads over on the tuner board has "some" merit, but only if they cut the ever livin dog sh*t out of your head, and at that point, you've got other problems... That said, I have always removed casting flash/radiused that area, as well a few areas in the block and front cover to reduce turbulence/aeriation of the oil.
Your mileage will vary, but cutting the spring is a very bad idea! It will cut the volume of oil headed into the motor, and that's just bad bidness right there.