I've got the -15mm Eibach Pro springs as well on the FN2 on 18's. Ride much better, but you will probably find particularly at the front you scrape curbs , driveways , occasionally turns into side roads etc
I park on street ( its a hill ) and have to park slightly on the pavement, cant get it on the pavement since fitting the -15mm going forwards due to scraping, have to reverse in. Plus have scraped the front a few times in parking spaces where the splitter would have just cleared the curb at the front before. Have got the GP kit on so maybe it makes it slightly worse for scraping, dont know.
Had new tyres last week and the fitters had a bit of trouble backing it off the ramp as it wanted to scrape the underside in the middle.
Dont know how people cope with the -30mm springs !