I’d start the serious mods path with investing in Btssm or Romraider.
In order to mod and get tuned for mods, you need to establish your current state of tune via health checks and logging, and maintain that state after the tune where you’re generally running the car with more power and less headroom for contingencies.
Since you’re just coming off your P’s, I’d hold off on the turbo upgrade for now, as ime it’s going to be plenty of fun with exhaust and intake mods and a tune. It’s been enough to satisfy my requirements for the last 8 years.
Some of this is because the tune is so good. The car is perfectly useable in all modes, at 7, 12 and 15 psi via the SI-drive controller, it never gets old
Its probably making 160wkw which suits my skill set and budget for maintenance perfectly.
I guess I find as much enjoyment from the driveline and suspension mods which along with the responsive vf46 seem to be the perfect balance for my use case, hauling gear around Victoria.
As for handling mods, just upgrade any worn out stock relieved bushes with solid poly items, eg front lca rear position, the diff bushes, pitch stop and transmission mount.
You’ll know when your stock suspension is wallowy on bumps and is crashing on big bumps.
Generally when you feel it’s limiting your options and enjoyment.
Get the very best dampers you can afford and that’s it.
Our GT is on Shockworks and our 2.5i is on Koni Yellows.
No need to reinvent your handling and chassis dynamics with uprated swaybars, if your dampers are capable.
Due to the limited suspension travel on a gen4, keeping as much compliance as possible is a good thing for grip and comfort.
Member STiful just went through the vf52 upgrade process, maybe check his posts for the considerations encountered.
Using a Perrin or psr v2 silicone inlet (more affordable) should maintain the correct pressure differential in the inlet for the pcv returns, meaning less reliance on an aos/cc setup for a street driven car not running e85, (edit) and running stock-ish boost. Going over 20psi max boost, yes verified aos/cc setup to suit your application is indeed a good idea, mainly because at high boost you’ll (sooner or later) be likely to have a built engine.
How soon is related to your budget, application and knock monitoring and prevention strategy. See below.
Anyhow, back to the question, you’ll want to install a wbo2 in your dump pipe and preferably log it via the ecu.
And potentially use a knock monitoring device, since a 1.5xtr with any of the optional exhaust housings is capable of making serious power, power which needs close monitoring so as not to blow your stock engine.
Similarly your driveline will be close to the limit, so you must ask yourself if making over 200wkw is the right move financially, when an $800 vf52 would probably have enough response & top end, plus general reliability.
So what’s your intended use case and budget?