I've been riding 2020 fanatic grip 92 since last autumn and I love it with the quad setup when I'm fully lit, it has loads of control when overpowered even with a 4.2. However, I find it a bit challenging to get/keep planning or going upwind when I am slightly underpowered. My understanding is that the thruster setup should help with that and also make it glide a touch longer when bottom turning (though I suppose improving my technique would also help with that).
I weigh 82 kg (without a wetsuit and we often need a thick one) and sail mostly in the side-onshore conditions, sometimes with strong currents.
I already have the recommended side fins from my freewave stb, so I'd only need to buy the central fin. I see that recommendations suggest using an 18cm central fin. Which sail sizes this recommendation is based on? Does it make sense to take a fin that is bigger than 18cm for 5.3 (or even 6.0 bump and jump conditions)?