I've got the basic techniques of slap pretty much mastered. I can slap and pop pretty easily. The problem I've hit is with ghost notes which no amount of practice seems to have made me any better at doing. I end up with a muddy sounding thud noise. I'm aware that it involves muting the string with the full set of fingers of the left hand but otherwise, I'm stuck.
Something that's also throwing me is speed. Again, no amount of practicing seems to have made this any better and I'm still ridiculously slow as a result. I've even tried different books, learning well-known slap-bass songs (Mr Pink by Level 42 being the most recent) and nothing seems to improve.
What's possibly the most frustrating for me is that in addition to me being a bassist, I'm a massive fan of Level 42 and Mark King, and to be unable to play L42's signature bass sound is so annoying. I've even tried copying Mark King directly which didn't help.