No, not asymmetrical fins like the K4 Ezzy fins, but rather on a quad moving the bottom turn fins closer together and the top turn fins further apart. I got the idea from a video posted here on Seabreeze and I've got to say it works great. I'm now running a 15.5 Incinerator rear and 8 cm Incinerator thruster on my bottom turn side, and the OEM G10 16 cm and 10 cm fins on the top turn side. I used to think my board was too stiff but now I love it.

Yes, guilty!
Totally worth exploring as bottom/top turn sides can very well benefit from a bit off tinkering to fit their respective requirements/sweet spot setups with all fins similar/only config.
Additional tweaking by size, softness, outline....it's result oriented fun imo if you dispose of a fin collection (K4 yellow plastics here.)

It's the proverbial "there is more in you" towards any multi-fin board.
Always surprised by the reticence of some to try even the smallest deviation from assumed manufacturer omniscience.

Since I always seem to need quite a bit of fin for side-on in very curious about anything that can loosen a board for the bottom turn.

Grantmac said..
Since I always seem to need quite a bit of fin for side-on in very curious about anything that can loosen a board for the bottom turn.

I'm going to hazard a guess that you should try leaving the bottom turn fins a fairly standard size (or if like me your board feels stiff initiating the bottom turn then go smaller and or flexier) and then pick a bigger rear fin on the top turn side so that you have enough fin area for the current/side on conditions?

Not sure about thrusters. Every time I've tried to make a thruster looser with bigger symmetrical side fins or bigger asymmetric side fins, I've had to down size the middle fin. Net result has always impacted early planing. But I've never tried different sized thrusters on a thruster board.