you guys are fun e .who's trump .or is that short for trumpeter ? it s a fish ? right ...

nerdy ,a lot of slalom boards you buy now a days ,don't come with a fin ,eg.. patrik ,exocet ,etc
yes ,is your answer ..I have a 105 rocket ,34 fin was supplies .but use a 32 or 30 if it howls ..with a 5,5 or 5,0 .also depends on the area of the fin .
i don't like the original fin that came with the board ,so i use a 34 select free ride .
another example, i use a 40 on my 115 patrik with the 7,5
then with the 6,5 i use the 36 .or a 26 delta
keeping your board down and in control is important .
if you have too much lift and fighting your board drop the fin down in size .