I have a cheap board and recently glassed around my right side fin to fix a hole. The right fin is now really rigid compared to the left. Surfing today I felt the board turned very easily to the right, it this my imagination or does the stiffness of the fin make such a big difference?
.. and it should have good drive when going right bottom turning and feel a bit soft and slidy when turning off the top.. 
Hey Andy, I picked this link up from one of the breeze forums a while back and provides a pretty good summary on the surfboard fin and how different shapes, flex etc effect the performance of the board.
allaboutsurfboards.com/surfboard-fin-design/
Do fins really make much difference?
Took a board down to the beach the other day forgetting the fins had been removed 
Too nice not to have a paddle -
YES fins definitely make a difference 
i believe the fins do make a difference, was running with a the set of fins that came with my board, they where alright, i brought a new set of k2.1 fins and i believe that my surfing has improved, but i can noticably fell more drive, while they also hold better in turns etc
Jarryd
Yes. Fins make a massive difference. One you have your board and paddle all sorted the fins are the next thing that you need to tweak until they are just perfect for you.
Fins can change characteristics of the board such as how well it holds, the tightness that the board turns and how well it drives. All of these things when they are set up perfect for you, can make a huge overall difference in your performance on the wave.
Marcel
