In some turbo systems, it may be necessary to restrict the oil supply side of the system to prevent oil leaks and smoking. Special flare jet -4 AN style jet holders are available, w/ several optional restrictors to fine tune the oiling system (similar in design to a nitrous style Flare Jet, except in a larger -4 AN size). These adjustable restrictor jets & holders may also work in some EFI applications to dampen the signal for remote mounted sensors.