My car handles beautifully try this, in this order. Take your car to BBR and get the BBR powergrip suspension, it works, take my word for it. its stunning and worth every penny.
www.BBRgti.com
Then change your wheels and tyres for some oz superlegerra (superlight) 18in wheels and Toyo Proxes t1-s tyres.
(wheelbase in oldham)
fit a strutbrace (i use one with a mini emblem, had great results cost £180 though)
(minisport)
Finally set your tyre pressures to 28psi front and back. (this is very critical 1 psi out makes a noticeable difference.