I’m not familiar with the KYB parts but one of the most common issues with springs is fitting front and rear the wrong way round, leaving the rear sitting far too high.
I hope you won’t feel insulted if I suggest it, but it catches so many people out that it’s worth mentioning. The stock springs, and many aftermarket sets too, use a longer, softer spring on the rear and a shorter, stiffer spring on the front. People presumably fit the long spring on the long shock and vice versa without double-checking.