XL Performance Rear Sponsons

(4 customer reviews)


Improve your standups stability and turning grip with the XL Rear Sponsons for vintage skis. The sponsons mount on top of the bond flange / rail to keep the stock lean angle while improving rear grip. We recommend installing these sponsons using our proven silicone adhesive.


Our performance XL rear sponson kit is designed to improve the riders confidence when riding their stand up watercraft.  These performance XL rear sponsons offer improved turning grip, better stability in a straight line and when leaning over in a turn. The difference between us and the other options on the market is grip and while turning at high speeds the ski is easier to lean which makes the ride smoother through the complete turn. The HFC sponson bolts to the top of the bond flange and it comes with a hardware kit.

What You Need to Know:

  • For the warranty, you need to install this product with our approved silicone. Apply silicone to all the edges and wipe off any excess from the surface of the product after installation. Smooth out any excess silicone along the edges as well. Allow the silicone 24 hours to cure.
  • This product does not include a cutout for the 550 H.I.N. tags. You can modify the parts easily but this will void the warranty. Otherwise, you can mount them in front of the tags with no performance loss.
  • If you have a 650SX and still have stock bumpers, you will need to remove or modify the bumpers to mount this sponson kit.

  • This product fits: Kawasaki 440 / 550 (all years) (other models not confirmed)
  • Installation time: 30 – 45 minutes
  • Hardware included.

  • What is the difference between this product and the OBF (Over the Bond Flange) sponsons?
    These XL Performance Rear Sponsons are designed for general riding up through racing with a more flat turning angle and better stability. The OBF sponsons provide similar rear grip in the turns but allow for full lean in the turns and corners. The XL rears are recommended over the OBF sponsons for vintage skis.
  • Is this part legal to race with?
    You will need to check the rules from your racing organization to verify if this part is legal for competition. ProWatercraft takes no responsibility if you are disqualified from this part breaking any racing organization rules.

Additional information

Weight 7 lbs
Dimensions 24 × 5 × 3 in


4 reviews for XL Performance Rear Sponsons

  1. Bryson Olson

    Must have if you’re a vintage racer. These will completely lock the rear end of the Skis down in the turns if you lay the ski over causing you to hook up instead of slide out. Also in rough water they made the ski stand very up right and not wanting to roll like the 550s do at high speeds. Definitely recommend these to any 550 rider/racer

  2. Kevin Knopf

    These will completely change how your ski rides FOR THE BETTER!! Amazing grip in turns, stability at higher speeds.. what more could you want!?

    Best money I’ve spent on my ski this far.

  3. Brandon McDonald (verified owner)

    I had the Original version for years but the new version is well refined! I like to get Rad and shred. these sponsons help the ski not feel like a 2 X 4 in the straights but also keep the ski planted while carving. A must have for conversion 550s.

  4. Jonathan (verified owner)

    I just got a set today went to install and the hardware junk iv stripped 2 head as well and the thread the lock nuts will eat the thread. But other then that I really like it can’t wait to put un the water tomorrow

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