I love my York. I haven't had any problem with oil being discharged. I think I've got the mod done to reduce the oil output. My filter/seperator has a trace amount of oil in it. I did put an unloader/check valve on the output. Its probably not necessary since an unloader is usually installed to reduce startup torque when coupled to an electric motor. A regular check valve would be as good. I have had the unloader portion stick a bit and continue to dump air when the compressor is running. It might be due to the way I have it plumbed. The 2.5 gal storage tank is way in the back plumbed with a 3/8 line. I used a cheap pressure switch to control the compressor that is set to 80/100 psi. I've got a safety release valve set to 125 psi. I used an illuminated ARB switch to turn the thing on but I've got a nasty voltage back spike that'll likely blow out the light bulb soon. I tried adding a diode to stop the spike but the light still has a really bright flash when I turn it off.
The pressure switch and filter are mounted on the firewall. I used a steel braided hose to go from the compressor to the filter housing because I wanted something that would maintain strength at high underhood temps.
'03 KTM 450EXC
"If you know what you're doing, then you aren't learning anything." - A. Lincoln