Hi,

I cant begin to imagine cranckase pressure high enough to prevent the oil draining back through the normal route for aftermarket breathers!!! Not unless of course your engine is totally shot causing a serious amount of blowby, you will be needing more than a breather kit to sort that

A four cylinder engine (even turbocharged) keeps the very slight cranckase pressure fairly even throughout the engine so this should not be an issue. Also some aftermarket oil temp gauges need the sump plug adapted for the sender units

I reckon it is wise to get a breather in the top of the engine, A lot of condensation gathers here and creates that mayo crap.

I had a billet alloy oil filler cap made up with a swivel coupling and take off pipe for the breather as I didn't want to drill out my cam cover, this works very well, and mayo is not an issue in my engine

The swivel coupling allows me to remove the filler cap to top up oil without disconnecting the breather pipe.

CheeRS, Mike