There is a law against aftermarket seats in Australia? And weld in cages aren't permitted? And the cars in Race King's link definitely didn't look road worthy...
Any car that has a wing stuck on it before all previous work has been completed is badly prepared and sticking wings and bodykits on without thinking about the aerodynamic effects is doubly silly. I bet none of those cars have had any kind of serious analysis that has come to the conclusion they need to use considerably larger side skirts, air dams and rear wings than equivalent race cars.
As I suspected - that spreadsheet is thorough ancient, so unless you've updated it yourself with the values for the current XRT in 0.5Z, it is incorrect. VHPA is much more up to date, I suggest you give that a try. Link in sig.
It's something either Colcob or I came across back in the day, and I think only really applies to road cars. I wrote it in my LFS setup guide but it won't be in the revised version (whenever I get the time to get on with that).
Your refering to real time attack cars and im refering to street legal cars, xrt doesnt have diffusers etc, thats all in reference.
Also having a wing, canards bodykit is better than having nothing, a real time attack car would be completly illegal to drive on the street, for starters it wont have a cat converter and the exhaust will be over 90bc, half cage is street legal but full cage is completely illegal even if its engineered, lsd's are another defect, acrylic windows are illegal, any sort of chassis modification are illegal, ride height too low is illegal, emmissions needs to be test which will most likely fail, canards and splitters are illegal.
Fiberglass or any over poly or carbon body fabrications are illegal, etc.
In superlap yes some cars should not be on the street but their nothing like a full prep racing car, I was not even talking about this lol
You think people can do these things for a living and hire some f1 driver so your happy. All I can say is at least im doing what I like unlike some. No one cares what you think suspension settings should be or what is required, just because it might work you it doesn't mean it will work for others.
We've gone very off topic here, your car (before and after your modifications) and other time attack cars all bear very little resemblance to the XRT and starting by creating a base setup using the recommended methods in Bob's Setup Guide and VHPA will get you off to a better start than trying to use whatever you're running on your unrelated real car.
Little confused by this post, is your car road legal? It has what I would have thought would be the issues with having a full rollcage, front legs and prop bars on the front legs and between the front legs and hoop. Though it's not very clear from the photo you definitly have a cross on the hoop and backstays, assuming you've got side bars you're running a full (welded?) competition cage. Chassis modifications usually are more about removing or moving existing chassis parts rather than adding new.
I think some of the confusion has arrisen because Time Attack in the UK/Japan is different to the Australlian series. In the photo gallery you've posted few of the cars have stupidly big wings and bodykits or chrome wheels like in the UK series (where it runs with boy racer/tuning shows) or in the Japanese video someone linked to. Your car doesn't have a silly bodykit, big wing or chrome wheels and looks like it does have a full cage, what you need! I just hope your not running standard manifolds with that tin can on the rear...