H&R sports springs…….Experiences ?

Hello everyone ! I intend to install a set of sports springs from H&R on my modest vehicle (Seat Léon Cupra 4 V6), at the same time with a wheel set 18 inches with the 1000miglia rims model “EVO 5”. Now I read in my forum that such springs are frowned on, at least in part. Some talk about a worse driving behaviour at higher speeds. I asked extra about 2 colleagues who have both springs in it, a Subaru Impreza GT and also a Leon Cupra. Both are completely z It is absolutely clear to me that a complete chassis is always better, but why should I throw out a good series suspension like that of the Cupra (S3 is certainly just as good) and give away too much money, I just want the box a little deeper, but not so that it is lying on the wheels, only about 30 mm less, to minimize the distance tire/wheelhouse. I can’t believe that this should be a “bad” solution, what does it mean? R ?