FCS Quad Fins

Aloha everyone,

 Just got a new Tokoro 6 8 bat tail HP Quad surfboard. Still havent figured out the right fin set up.Using a Scarfini HX 3 quad set that a surf shop guy talked me into getting. To put it bluntly, they SUCK! Makes the board way too loose and very little drive. Any body recommend an FCS base fin to stiffen the board up and increase drive? I am 200 pounds and have ridden thrusters most of my surfing life. Looking at the Rusty Fins. Any recommendations would be appreciated!

Mahalo