Results - i've changed a few things, but this definitely worked.
I used to fill up my catch can in around 3 laps. Now I can do 3 laps and there is Zero (completely zero) in the catch can.
I need to work out exactly what caused the biggest impact.

Things I changed:
1) New EFR7670 setup. EMAP went from ~400kpa to around ~300kpa (15psi reduction) over a stock frame turbo - Intense 5353.
2) New Athena/Vulcan ring headgasket. My old Tomei headgasket failed @ 500ftlb torque at low-ish rpm (3500rpm), leakage around #4 cylinder into the coolant system.
3) Blocked the lifter bleed holes at the end of the gallery. No negative effect, no ticking etc.
4) New baffle system for my Hypertune rocker cover

I dont know if points 1) and 2) will have an impact on blowby at all. Maybe?

Pics of the new baffles I made are below. They have 3x breathing ports per plate with side shrouds that extend down and over the camshafts like OE.
This was the stop the oil flicked off the camshaft lobes to get above the baffles.
Also there is "hurdles" on top of the baffle plate, so the oil needs to climb over multiple hurdles to get to the catch can.
Some of the hurdles have holes at the base of them to promote any liquid oil above the baffle plate to drop back down into the head.


New baffle plates showing the half moons to shroud the camshaft lobes, and the hurdles to stop liquid oil coming out the breather lines.

 

I think it all helps a little bit in their own way. I think the main goal of the OE baffles it to reduce the oil crawling on the ceiling of the VC, also give the air current a few sharp turns. looking at the stains on my baffle plate it looked like oil pools in some areas

 

That's a clever solution.

Though I have to ask: Did you have anything equally clean in mind for removing the bearing if it doesn't work out?

 

Changing the turbo would have no effect. Reducing Emap doesn't change cylinder pressure. You just allowed more fresh air in.

 

No sir I do not! haha
I was fairly certain it would work, so I just went for it.

 

do we want more oil limiting than what the kiggly hla is already providing?

 

My gut says no, at some point the lifters won't be able to stay pumped up if even less oil makes it into the head.

 

blocking the end of the lifter gallery's does not change the oil pressure to the lifters or the camshafts.
The oil pressure at the lifters is regulated by the Kiggly HLA.
Blocking those 2x holes is just reducing how much oil is being "wasted" in the head.

 

First day out on slicks, I got one session in before it started raining.
Car went really well, very little oil in the catch can (less than 100ml) since making those changes.
PB went from 1:10.3 to 1:08.6 going from semi slicks to Yokohama slicks. 260/640R17 size.

Just need to sort out my brake temps now, and more chassis/suspension changes to help get rid of that front end rumble when commanding too much steering angle.
I'll be playing with shock settings, I'm running 3-way Reinharte's at the moment with 12kg front and 18kg rear. Will likely change the rear to 22kg or 24kg springs to get the balance better.
My local track (Hampton Downs) is smooth and clean, so heavy spring rates seems to work well here.

Oil pressure is still perfect, no oil surge even running on slicks.
Note: My oil pressure reads lower because I have the sensor on the end of the mains gallery (#4 cylinder). And I'm running a Tomei Thermostat killer which increases the pressure drop as all oil is forced through the oil cooler. 65psi at the mains is around 85psi at the oil filter housing.
The small "dips" in the oil pressure is from the Mivec activation/movement.

 

I would bump your regulator up a bit, another 10-15psi wouldn't hurt anything. Get it to around 100 at the OFH, more pressure to keep the bearings happy.

 

Hmm does this mean IMAP increased?

 

IMAP is reduced, running approx 15psi boost is the same power as the old setup on around 19-20psi.

 

Yup agreed, normally with new oil the pressure comes up a little.
Pics of the #4 big-end bearings about 4 weeks ago. These have done ~10years and probably 50 track days.
Only moderate power at around 380-450whp, but i'm very happy with how they look.

 

They look okay, certainly for the use. But the wear on the cap side shell indicates possible insufficient oiling.

 

Makes sense I got mixed up with a IMAP/EMAP thread before this.

So Mass flow rate was increased with lower IMAP and EMAP this sounds like a win.