How much is 2-3 cm deeper and 2 cm wider?

Hello What do it cost, if you want to lay a TT 2 to 3 cm lower? Then only other springs have to go in, right? How does the driving behaviour change? Or is it fundamentally advised not to do so and you should only change complete suspensions? And what does the installation of the distance discs of which one reads a lot here? Is this with ABE or do you have to drive in front of the TÜV? Greetings Michael