there is..
and not true. there are a few other brands that run a similar idea (all be it more modden).
It all depends on what YOU want from the car.
Assuming your car is stock (motor) and the gts4 is then you will find it slower than the gtst because of all the fwd gear. you can run stagered wheel sizes as long as the ROLLING diameter is the same.
So why do you want a gts4? plan on putting a rb26 or something in it?
what do you want from the car? you said grip but also the ability to use only rwd, why?