The first thing most people will do is add more power. Either by chip tuning or even more extensive.
Handling improvements usually come second. I did all with my Abarth. KONI shocks, stiffer springs and roll bars, tension bars between the struts, brake upgrade and engine tuning (polished intake channels, racing air intake filters, higher compression and forged Mahle pistons). Also a Sparco Racing seat with 4 point harness. In the end i did spend more on parts than the whole car was worth, not to mention the audio (Clarion and Macrom). But back than i liked doing that.
PS Never mount a real racing seat with harness in your daily car. Too much of a hassle every time.
Having no more brakes can be scary. I once had smoking wheel arches when driving down a mountain road. I had to stop the car as the brakes were red hot and i had almost zero deceleration left. That is beyond fading...
Maybe doing over 100MPH downhill is not the wise thing to do anyway.