[Perfectlap]

thats because he wants to see you come in and buy a new top!

Replacing the softtop is an entirely preventable expense.
Raggtopp is the only product endorsed by the makers of your canvas top.
I think the Porsche brand protectant is rebranded Raggtopp.

Well anyhoo Raggtopp is like a scotch guard coating. It won't prevent sun
damage (use of a soft top cover will help BIG TIME) but it keeps contaminants out of the threads. Check ebay for the soft top cover in a "Boxster cover" search.
Don't use the door fasteners if you do get one, it'll just marr the paint there.

Car wash soap is the last thing you want on canvas. That stuff is for paint and glass. Like most soaps, car wash detergents attract dust which leads to the threads breaking down and thining and then the friction from the bows starts to tear the canvas.