Nah. The designers did well enough. If your bike's breathing is inadequate, something's not right.
Actually this is one time when they did not .
The factory breather really only works well up to 1/3 throttle, barely works to 2/3 throttle and works backwards over 2/3 throttle.
Rex did a lot of work before he handed the project over to Auckland University where they did extensive testing revealing the above.
Now the caveat to this is the bulk of the time we ride at 2/3 throttle or less so it will do, although it could be better.
Weather it is worthwhile to muck around with breathing depends very much on the rider.
If you are WFO type of rider ( ie Musky ) then it is worthwhile and will substantially reduce leaking & oil burning.
On A7/10's proper breathing will end the infamous rocker box leaking that bedevils a lot of owners.
The idea of creating a partial vacuum in the crankcase comes from the days of long stroke engines that had no oil seals and had a rev ceiling in the order of 5000 rpm.
Thus the engine was designed to perpetually suck air in through all of the slingers & blow it out the breather past an unsprung almost one way valve.
Crankcase venting is every bit as complicated as induction breathing and exhaust tuning.
As such it is very difficult to design system that will work properly all the way from idle through to valve bounce.
The through flow design with check valves is the only system that has the ability to work over the entire rev range.
No mechanically timed system can work properly over the entire rev range because air has mass and therefore there is a latency and momentum effect which gets more pronounced the higher the revs.
On the A 10 tested near 1.5 Hp is gobbled up by the ineffective breathing system at peak revs.
Now back when the bikes were new, leaving a puddle of oil on the ground after a good "high spirited" ride was acceptable .
However leaving a pool of oil when at idle on the showroom floor was not.
Thus a breathing system that works best just off idle.
