If it's powerful and reliable as well as decent build quality it might win some decent fans that are not already attached to a brand too hard - either new drivers or those that are happy to swap badges. People like myself who love Fords tragically and don't like the idea of buying another brand will be harder to convince. I respect any car can can give me a run for my money down the drag strip, but that's just me. Has to be pretty special to want to buy one...I'd love a Dodge Hellcat or Demon.
As for modding the Kia Stinger for more power - if the engine has decent power it might not have much left in terms of tune-ability if it's already at the pointy end of what the components can withstand.
Time will possibly bring the goods though, as we saw with B series modded power levels increasing massively from 2002 to 2008! 300rwkw and 11 second quarters used to be impressive, now it's barely worth mentioning unless it's to someone that has never modified!
Luckily an 11 second car still feels fairly impressive to passengers that haven't gone for a spin in a powerful car yet