Tuning!!!

Hi guys! From February I start with tuning! Then finally there’s coal!! First I wanted to start with deeper laying, then Car-Hifi, then let engine-haupe and rear bumper paint and when spring comes there’s chic 17 -or 18 inches!! Anyway here first my questions to lay deeper: I thought of 40mm deeper laying by springs. Over 60 mm have already been complained about here that the shock absorbers suffer. Or what do you say about it? Why is that so? expensive are well feders and where do I get them?? 2) Or can you recommend me an alternative!! New chassis!! What does the fun cost about and is so much better?? Thank you in advance for your answers!! Greeting Iceman