As above, get some miles and get a feel for it before splashing out on mods.
I've had my 10 year old GSXR 750 since new, and it's still on all the original parts other than braided front brake lines and a slip-on exhaust. It's been well looked after and had some minor work done to the rear shock linkage but thats it. The brakes on that model also got slagged for lacking feel & power, but I've never had a problem and it still pulls a stoppie with only 2 fingers on the lever. That said, the front discs are aging and becoming worn so I will be upgrading the discs and master cylinder over winter.
A good tip is to use a rag to tie back the lever to the grip overnight, by keeping constant pressure on it will f0rce any trapped air bubbles out giving you a noticible improvement, gratis.
Beware that using super-duper racing pads on stock discs could lead to warping, at least thats what I blamed the two warped discs on my old bike on.
Also I'd steer clear of full exhaust systems (unless it's road legal) otherwise MOT time is a nightmare. Been there, done that and had the snapped exhaust header bolt to prove it. Any performance increase will be negligible on a bike of that age and will also involve adjusting the fueling. If you want performance then better saving the pennies up for a more sporty model.
Hope this is of some help
