If you have an Evolution with about 20,000 miles on it, you have a base gasket leak!
The factory has tried to remedy this problem with at least four different styles of cylinder studs to no avail
Eliminates top end drain back oil from even touching the base gasket
For best results use with metal base gaskets
Tap the cylinder in the top end oil drain back hole with the supplied aluminum tap and install
the PigTail with about one inch left protruding to be inserted into the crankcase
Can be easily removed for cylinder service
Designed for OE style cylinders (not intended for big bore cylinders)