I had the same problem. 7 laps of Symmons would put about 2.5 ltr into the catch can. Its a 25/30. It was just built. the standard rb30 restrictors (I think they are 1.8) was left in. It does have the head drain back to side of block. I tried a few things but had no luck. I ended up running drain on the catch can back to the sump. ran all of 09 season like this.
The start of this year I spun a rod bearing, so It was rebuild time again. this time 1mm restrictors went in. Still runs the back of head drain back to block. I also Put RB 26 covers with mines baffles. pissed off the oil return from catch can to the sump. Had its first race meet today, and not 1 drop of oil in the catch can.
I am running a N1 pump. Edge 10/60 oil.