Taylor,
It's not at all about stance, last of my worries.... not running stretched tyres like them idiots and not lowering it stupidly.

It's all about deep concave wheels!

Here's how:
9.5 rim with the right offset (+33~+20) and tyre size/profile (255/35) gives you that ultra concave look without affecting performance(assuming), driveability, and even the speedometer which is almost on par with that config (.0022% difference in speedo reading [winning!]).

And best of all is that the tyre comes to the exact same height to the strut as your stock wheels while being a few millimetres further away from the strut, so your stock suspension takes it no problems.
As a comparison for you guys running 18x8.5 with 245 40 tyres - your tire is well above what your normal OEM tire would be, hence why you need coilovers for sure as it otherwise will rub with the spring seat

The guards will have to be rolled and camber bolts will have to be used, nothing more in the immediate, but will eventually need coilovers as bounce/suspension travel will be an issue with passengers in the car. You don't want anything with more offset than +30 as it will be a guard fitting mission with a 9.5, a +30 is the perfect fit.

Thats what I've gathered from asking around and also what the rim manufacturer advised. Although I do realise that it may not be so easy or in reality its a headache, hence why I'm test fitting some first.

Please anyone correct me if I'm wrong about any of this if you have tried this combo or if it will affect performance even if they are much lighter JDM wheels?

There are cars on pwrx running that configuration from what I saw in the wheels thread, but most haven't dropped to the right 35 profile while increasing their tread size and have had to run massive camber.

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06 STi: 337hp @23psi on E85...
06 STi: 309hp @22psi on 98ron...