I think your restrictor is a little too small. Per the following source, it appears as though 0.078" or around that is a good restrictor size for Garrett turbos that require it:

http://www.dsmtuners.com/forums/showthread.php?t=171317

Many people get away with just drilling out an oil inlet flange to their desired specifications. While over-lubrication can be a serious problem, for standard journal bearing turbos, under-lubrications seems much more harmful.

Ball bearing turbos are the ones you'd want to use such a small restrictor for...