****UPDATE****
I have had the OEM suspension replaced with KYB Excels and King springs. I also added a rear trunk tower brace.
The shorter springs meant that the front brace couldn't clear most speed humps without having to virtually stop the car, and some savage humps on the rooftop car park of Westfields Chatswood pushed the mid brace onto the cat and I had to limp home making all sorts of vibrational noise
.
I took the car straight to my fave guys at Marks & Wallings in Artarmon where the diagnosis was simple: remove the braces and redo the wheel alignment... I was out of there in 30 mins with no booking etc.
So, now I have front and rear tower braces, progressive lowered springs and new OEM style shocks.
Removing the braces didn't alter the feel or dynamic of the new setup.
The car feels great and clears all speed humps easily. Phew! I hated the lack of clearance issues.
All is good for now and I can see new sways on the horizon, but no hurry here.