Congrats on your Polo. I wish you spend many happy miles with it.
I have seen a few silver Polos on the road. The finish of the silver paint is amazing. On aa lighter note therefore, the cost of denting/painting this colour would also be amazing.
Don't go for any tuning kit. It would almost 100% void your warranty. Enjoy your car stock. Volkswagens are very expensive to maintain and therefore if anything happens to your car and the warranty gets void due to installation of the tuning kit, you'd be looking at five digit figures for repairs to your car. Volkswagen dealers show no mercy in extracting money from owners of its cars.
P.s.: Take the extended warranty. You'll thank me later.