I don’t mean to bump and ancient conversation but I have been struggling with this same situation and found this all very valuable. Jim Russell’s comment above is great.
I moved from a tillet seat to a ribtect and then took my kart and my seat to my local shop and had them install it for me on some scales so that I knew a legit pro shop. This helped a lot as the shop set my seat up with more “lean back” and I prefer the ribtect seat.
One thing that I think has helped me is adding footrests/heal cups. This allows me to brace myself in long sweeping turns a bit more by pushing myself back into my seat with my outside foot and allows me to relax my hands a bit and be more sensitive to what the kart is doing.
can a kart seat be too tight in regards to it not allowing the kart chassis to flex properly? my seat is tight and I like it that way but it is a very tight fit