IIRC, there is no Dynojet kit for the FZS but a K&N with a non-standard exhaust makes a big difference to the power characteristics of the 600cc engine.
Some of the toys you can get are Digi-Gear indicator (OK if you cannot count), differnt screens to give different wind buffeting, loud exhausts, heated grips, panniers and boxes, crash bungs, lower fairings, belly pans, anodised bolt kits, scottoilers, different gearing through changing the sprokets, custom seats, etc etc etc.