Hi – an aftermarket suspension kit really improves the GTA. I found that the standard suspension made the steering go light over mid-corner bumps – not what you want with a car with the weight distribution of a lump hammer. I went with the Eibach Prostreet-S coilover kit with upgraded ARBs from Autolusso. At the time I had the (silly) idea of going on track days with it; it's not really a car for that. I'm not going to lie, the low-speed ride is harsh, but the standard suspension wasn't much better. However, that mid-corner floatiness has completely gone and there's much greater feedback through the steering wheel now. It might still be too harsh (the Koni FSD cars I've tried have offered a good compromise), but the transformative effects on the handling are immeasurable. It's well worth upgrading to a non-standard setup, but it's not essential (like the Q2). The good thing about the Eibach kit is that it can be adjusted for ride height; not sure about the Koni ones. I've not tried the Ohlins.
You're welcome to try mine but I'm not happy with the tyres; I've Toyo T1-Rs (or whatever the latest is called) and it's squealing under cornering on those after less than 1500 miles and the turn-in is a bit mushy. I think I'm gonna have to hold my nose and take the Michelin route. It had Pirelli P-Zeroes on before, and they made it a bit Audi-like.