Not much avaliable for the 197 off the shelf 2b honest mate. But from what i know...
Engine: Leave the induction kits alone, they've only been proven to lose BHP unless you relocate the battery for a cold air feed, big hassle. Panel filter will suffice. matching the inlets works well but its pricey at £250+.
Brakes:Uprating pads is popular and the Ferodo DS2500 are a good choice, apart from that theres not much else worth doing.
Suspension: Lowering springs avaliable, Eibach are only £170 and very good quality. Coilovers are expensive but give you much better stance and handling.
Exhaust: K-tec and Milltek are most popular but require a remap due to the flat spot they create. Decats dont work well and most people steer clear of them 2bh.