High Performance vehicle naturally increase crankcase pressure and combustion events become more and more powerful along the various levels of builds and the OEM breather system was simply not designed to allow your turbocharged engine or high compression naturally aspirated engine to breathe like it needs to. In a case where the engine cannot sufficient release crankcase pressure, there is only a couple places it can relieve the pressure which are not good. That pressure will push past the rings and cause the engine to smoke which decreases ring seal as well as power output. That pressure will build up under the piston and act as a negative force the natural pumping pressures created through internal combustion. This oil contaminates your combustion event and can cause more harm than you would expect. Not to mention having a smokey car just isn't something that is pleasing.
This is a Honda H22 valve cover which got 2 -10AN bungs put in place for crankcase ventilation and the timing cover cut to expose the gears
Welding on valve covers is hit and miss even with the extensive prep I put into it but this would be considered decent!
Basic service for 2 bungs is $150+ return shipping and includes the cost of the bungs. Basic Honda timing cover cutting is an additional $25. I can offer other options like PCV billet plugs or welding a cover over the whole section. Removing the stock breather tube and welding closed and then blending smooth.
Oil dripping covers will he charged an additional clean up service fee. So do me a favor and soak the cover in purple power or some form of degreaser overnight before sending it to me.