DynoJet kit - I sense no difference, but spark plugs look OK so no harm either. Works OK.
K&N air filter - good one.
Open end can - really nice sound and a bit of performance gained (or more mpg when not driven hard). It sounds cool now. It also looks cool: a triangular carbon one!
What I'd love is new rear shock and new front fork springs. However, I can't find a way to justify to myself spending 700 euros on suspension on a bike that costs maybe twice that much. I'm not too heavy (70 kg), so the stock suspension is not all wrong for me. Still...
Yes, forgot: small indicators.
Both headlights mod - a no brainier, helps and looks nicer.
LED taillight bulbs - less power used, works neat and gives better contrast from normal to braking mode.
Mushroom looking sliders - no brainier.
Givi Topbox rack, with a 50 litre topbox (you have a woman, you need it
). Homemade soft panniers distancers so panniers don't cover rear blinkers.
Scottoiler - not sure if it's a real mod, but it helps.
OMG, didn't realise what has been done in years. Looks like a lot, but I wouldn't like the bike without it all.