If I were you , I wouldn't put 4.5" surf style fins on your Triple X 58 composite as that is a Skim board but you could get a bit longer fin which would make it more stable and catch the wake easier.
I actually put Hyperlite 4.5" landlock surf fins on it which I don' think they make any more:
http://www.boardstop.com/product_inf...oducts_id=1502
They were sold out everywhere online last year and I was surprised to find my local shop had some in stock.
It was an easy swap as they both have the two hole wakeboard fin configuration. I don't think you will have much luck w/ finding the 4.5" landlock fins but Ronix is now making replacement surf fins at 2.5" and 3.5"
http://www.boardstop.com/index.php?c...&source=google
Ideally, FCS for Future Fins would work best on a surf style board but removing 2 screws was much easier then installing future fin boxes or FCS plugs and the Hyperlite 4.5" fins work just fine.
Triple X is now making the Slasher with FCS 4.5" surf fins. It made no sense to put those 1.75" wakeboard fins on it.