Upgraded Suspension can be bought from numerous Companies, LEDA in the UK for example make a coilover kit for the K10, otherwise Monroe Dampers and new or lowering springs to add strength.
You could use pretty much any motorbike carbs, however maybe some from a CBR600 Honda, think Ed on here used those himself.
Mapped ignition, bike carbs, maybe new manifold and exhaust might give 30-40 bhp if you really lucky. Not sure what the stock bhp on the ga16ds but i should imagine you'll then be at 130bhp is, which would be pretty fast for a K10.
Mapped ignition would be Greddy e-manage or something similar.