The first and only real mod (so far) has been a full rip out and upgrade of the stereo. This allowed me to introduce an OEM looking reverse camera, sat nav head unit, compact 4 channel amp and replace the speakers with some nice JL's. This included the rears going up from the 3" coke can sized ones to 5.25" in some custom brackets.
The underlying desire was for it to look factory and not be a compromise by adding too much weight. This meant I could forgo the boot space eating sub and still have decent bass. Part of the install included the option of sound deadening, but I had no interest in adding 15kg worth of weight to a light car.
Looking down the line (to help with road noise) I'll be looking at better performance tires on lighter wheels (staying on 17's) and some nice quality coilovers, again for reducing noise, but also improve ride. Not looking to lower the car more than an inch (if at all).
By now you might be noticing a common theme or at least my own happy median being, to add something to improve the DD nature of the car, but in a quality way and to not mess with what makes the car great. I'm taking the good advise of simply enjoying the car and slowly improving parts to fit my needs / taste.
I also do a loooooot of reading / research so I do it right first time and am confident that I won't regret the mod later. Those 'what mod do you regret doing in hindsight' type threads are pretty awesome in this regard