Seadoo Sportster 1800 is too loud.

[LawnDart]

I don't understand why you wouldn't want to enjoy sweet sound of 2-stroke performance.

 

[To2d]

What about Dynamat installed under the rear tray?
Would this stuff work. It's soaks up noise from engine and is rated for temperature
http://www.dynamat.com/automotive-and-transportation/automotive-restoration/hoodliner/