Just figured out what was causing the rattling in the back of my S2K.

It was the thing that tightens the spare tire to the frame of the car. It was loose (not tightened all the way) so at high speeds it rattled..

Hope this might help some of you S2K owners..

 

OMG! Thank you so much! I can't believe I didn't think of that. I was trying to find the source of that rattle in the space behind the rollbars.

 

Sunchild another famous rattle is the passenger seat on the "cargo net" hook. Try moving your passenger seat up one click if it's not the spare tire.