I recently put some FCS MR TX side fins on my board after snapping one of the standard M7's.

First I tried it as a twin with no center fin and it was really fun in small waist high waves. Super loose, almost like a snowboard the way you could spin it around and tail slide everywhere. I loved the way it bottom turned too. The down side was it paddled in circles and I knew it would be no good once the waves got bigger.

So I added a 4.5" Futures center fin set in the middle of the fin box and took it out in some good shoulder to head high waves.
It went well and paddled similar to the standard set up ( M7's and 6 .5" Center fin ).

It felt a little too stiff off the top and much harder to slide the tail. My question is that I'm wondering whether moving the center fin all the way forward will make much of a difference to the drive of the board. With the standard set up I used to run it all the way forward and it was good up to overhead + a bit waves (3-4ft).
I plan to play around with the settings but Its hard to come in, make adjustments and go out again several times in a session so I thought some expert advice might speed up the process.

Thanks