I have been using the thruster set up more and more in bump & jump choppy conditions on my Kode 95 fsw. Often use single larger center fin with 5.7-6.5 conditions. Thruster set-up with smaller sails until I shift to my ultra Kode 82 under 4.7.

Just looking for tips on tuning the thruster. Currently I just follow the starboard markings (as in pic). Am I right in thinking moving the whole set back gives better control/direction, but just moving small fins back closer to center fin loosens up the board? I read in some places that moving the small fins forward is supposed to give more grip? In other places the opposite? What kind of distance is recommended between the fins?

Any tips or links to good thruster tuning would be gratefully received :)

When you read about moving the front fins forward to give more grip or drive, they mean when turning on the wave.
If you are not wave riding, don't worry about it, especially as that is talking about spreading the fins out wider, which is different to moving the whole set back or forward
For bump n jump, how you have the set is just fine.

From K4 website, a good short summary. Remember some of it is talking about feel in turns not straight line handling

The following is true for any fins and will help you get the best from your board..
Moving the fin cluster (1,2,3 or 4 fin) rearward will give your board more speed, more grip and more control. Better for big waves or big wind and perhaps for onshore conditions where drive and upwind are important.
Moving the fin cluster forward will make your board looser and skatier. Better for fun size waves and rippable conditions when nicely powered up.
Moving the fin cluster apart (tri and quads) will make the board feel more planted and stiffer. Better for large waves.
Moving the fin cluster together will make the board looser and with more pivot. Better for small waves.

FIN TEMPLATE
The outline of your fin makes a considerable difference to it's performance..
A wider base will give better drive and acceleration.
A narrower base more speed and pivot.
A more upright fin with less 'sweep' will give tighter turns and more pivot.
A more swept back fin will give better control and more sweeping wide arc turns.
More area will give more hold but be stiffer for a given length.
Fins with a longer tip out the back (or rake) will give more grip and direction, better for larger arcs and powerful carves.
Fins with less tip will be more snappy and turn tighter, better for staying in the critical section of small waves. They may also be faster.

norwaysail said..
I have been using the thruster set up more and more in bump & jump choppy conditions on my Kode 95 fsw. Often use single larger center fin with 5.7-6.5 conditions. Thruster set-up with smaller sails until I shift to my ultra Kode 82 under 4.7.

Just looking for tips on tuning the thruster. Currently I just follow the starboard markings (as in pic). Am I right in thinking moving the whole set back gives better control/direction, but just moving small fins back closer to center fin loosens up the board? I read in some places that moving the small fins forward is supposed to give more grip? In other places the opposite? What kind of distance is recommended between the fins?

Any tips or links to good thruster tuning would be gratefully received :)

Yes, back "fast" and forward more agile. I have a Kode FSW 81 and I use very small 6" K4 Shark side fins together with a Maui Ultra Fin X-wave 22. Anything bigger on the sides and I fell the board is dragged down. On my 90 RRD FSW I only use single fin (Maui Ultra Fin X-wave 25).