I've just ordered a 125 TSFI Q3, Monsoon Grey, S-Line, 18" alloys with Teknik Pack (Xenons, MMI plus etc) but I couldn't convince work to stump up more than $60K in total so I'll be doing a few aftermarket upgrades, like tinted windows and most importantly sound system upgrade.

I was wondering if anyone else has done this?

I presume it won't be too hard installing some new splits in the front and putting a sub under the seat (like this - TS-WX110A Space-saving Amplified Sub (150W) - Pioneer Car Speakers, Sub ) or one of those subs that fit in the spare wheel.

Would be nice to hear if anyone has any experience with this.