I decided that I still wasn't entirely happy with the relative positions/heights of the brake and accelerator pedals for heel-toe, even after changing from a 7/8 inch to a 1 inch master cylinder to firm up the pedal (it certainly helped significantly though).
I know plenty of people who are totally happy with the stock pedal positioning, but I concluded that I needed my brake pedal to be quite a lot higher. This is because when I depress the brake pedal firmly it goes well below the accelerator pedal, making it tricky to get my foot up and over the accelerator pedal to blip it while maintaining constant brake pressure. This would also depend on shoe size and the height of the driver (I'm ~6ft), due to the proximity of the knees to the steering column etc, which could explain why some people are happy with the stock pedal positioning while others aren't.
The pedal height adjusting nut was already maxed out on my car so I couldn't increase my brake pedal height any further without making modifications. I took some measurements and decided that I would need to increase the brake pedal height by as much as 30mm if I wanted the brake pedal and accelerator pedal to be nicely lined up when braking hard.
I ended up removing the brake pedal from the car (what a PITA!) and got a fab shop to weld on an 'extension' to increase the pedal height by about 30mm. They welded a 30mm length of RHS onto the existing metal plate that the rubber grip pad attaches to. Then they made a new metal plate of the same shape and welded it on to the RHS section, and the rubber grip pad attaches to this new plate. The original plate was then trimmed back to the welds around the RHS.
After reinstalling the brake pedal and going for a drive, at first it felt strange having the brake pedal 30mm higher in its static position, but it didn't take long for me to get used to it, and the relative heights of the brake and accelerator pedals felt almost perfect when braking, just as I'd hoped. My daily driver has the brake pedal 20-30mm higher than the accelerator pedal from the factory, which is one of the reasons why I knew that this idea wasn't as crazy as it sounds. 
If I wanted to, I could now use the pedal height adjusting nut to reduce the brake pedal height again, but I think I'll just leave it. 
 

 

 

Good job man!

I went for a random drive with Jaemus last night, and with the corrected wheel alignment and the softer damper settings I can now say that I've never been happier with how the car feels and handles on the street!
I also had my front tyres replaced last weekend because the previous tyres were worn down to the canvas on the inside only, due to the crazy amount of toe-out that I had before the wheel alignment. The new front tyres are Kumho Ecsta KU39, and my initial impressions are very positive. 

I have been running the KU39's on mine since I have had it and ran them on our STi previously and I have been very happy with them.
 
What size did you go with on the front still the 215 or did you manage to squeeze a 225 on it?

Nik_Lee
I have been running the KU39's on mine since I have had it and ran them on our STi previously and I have been very happy with them.

I forgot that you also had KU39s. It's good to know that you're happy with them after all this time. 
 

Nik_Lee
What size did you go with on the front still the 215 or did you manage to squeeze a 225 on it?

Yeah, still 215 tyres. It looks like I could've fitted a 225 with no trouble, but the sidewall is vertical with the 215 tyres so it may have looked a bit bulgy with 225 tyres. 

robk

Nik_Lee
I have been running the KU39's on mine since I have had it and ran them on our STi previously and I have been very happy with them.

I forgot that you also had KU39s. It's good to know that you're happy with them after all this time. 
 

Nik_Lee
What size did you go with on the front still the 215 or did you manage to squeeze a 225 on it?

Yeah, still 215 tyres. It looks like I could've fitted a 225 with no trouble, but the sidewall is vertical with the 215 tyres so it may have looked a bit bulgy with 225 tyres. 

Interesting!
Mine have a slight stretch look to them and I have been considering trying to see if I could fit a 225 next time around.

Nik_Lee

robk

Nik_Lee
I have been running the KU39's on mine since I have had it and ran them on our STi previously and I have been very happy with them.

I forgot that you also had KU39s. It's good to know that you're happy with them after all this time. 
 

Nik_Lee
What size did you go with on the front still the 215 or did you manage to squeeze a 225 on it?

Yeah, still 215 tyres. It looks like I could've fitted a 225 with no trouble, but the sidewall is vertical with the 215 tyres so it may have looked a bit bulgy with 225 tyres.

Interesting!
Mine have a slight stretch look to them and I have been considering trying to see if I could fit a 225 next time around.

After you mentioned it, I had a closer look at the sidewalls and you're right that they actually lean inwards slightly. So, a 225 tyre would probably be perfect with vertical sidewalls, rather than bulgy sidewalls as I said originally. With this in mind, I too will probably try 225 tyres up front next time.

Yesterday I bought an Ecliptech 'Shift-P2': https://ecliptech.com.au/shift-p2/
It's a progressive shift-light, with lots of features. I think some other people on this forum have the previous 'Shift-I' model.
I'll be installing the Shift-P2 on top of the steering column. They provide a 1:1 scale template which I printed and confirmed that it's a good spot where I can easily see it without blocking my view of anything on the dash cluster. 
If it arrives soon then I'll try to install it before the Wakefield Park Challenge. 
 
I also want to replace my power steering relay with a solid state relay, so I'll do that soon too. 
 
I'll update again after doing both of these things. 

robk
I also want to replace my power steering relay with a solid state relay, so I'll do that soon too. 

https://www.jaycar.com.au/solid-state-relay-4-32vdc-input-30vdc-100a-switching/p/SY4086
 

This reminds me I think I forgot to send you the details on the solid state relay I have been using in mine. sorry about that.
I am using a Stinger SGP38 80 Amp Battery Isolator and Relay here is a link to one and I have also seen a couple of electronics stores on ebay selling them.
https://www.elite-electronics.com.au/In-Car_Entertainment/Accessories/Capacitors/Stinger_SGP38_80_Amp_Battery_Isolator_and_Relay