I have been using a Perry VP30 regulating pump with a OS91FX with a tune pipe in a pattern plain for more than a year. The pump is in line from the tank which is on the CG. I had no problems adjusting it and only had to decrease its pump action by turning the hex screw out about 1 ½ turn. With 10% nitro the main needle it about 1 ½ turns open. Mixture is very constant and the oil that comes out the tune pipe is completely clear, my Plugs are lasting much longer.