Any single silencer exhaust system will pass a db test on a VTR, they arent loud.
Decat 4/2/1 mani and a supersprint/kam/saxsport would be my vote.
Standard brakes are fine with decent discs and pads.
Most common and most restricting fault with a VTR is a seized compensator valve causing the back end to lock up first.
If it were mine, i would strip it all out, service it, fit a 4/2/1 and exhaust system.
I would then fit this Kam suspension kit,
http://www.kamracing.co.uk/car-tunin...saxo-35mm.html
Lower the beam about 35mm
then sort 4 decent tires.
Be bang on!