I want too increase the performance of my 9N Polo classic 1.6
You are only going to get so much out of a 1.6L. Spend a fist-full of money for what? A few more HP? It will be nothing noticeable, in my humble opinion don't waste money on 'performance upgrades' that will both strain the rest of your drive-train and possibly not pass inspection.
Like Ford says you can spend a lot of money for a little more go but Check out the goodies here - http://www.carid.com/2013- volkswagen-polo-accessories/#spb_performanceparts