Not that I know of. Your 7 year old struts are probably just a bit weak and now you have the extra weight.
I just bought a pair for the front for my 1997. Got them on ebay. They are made by Stabilus just like the ones sold by Porsche, except I paid $39 for a pair and Porsche wants $39 for just one. Did not ask about the rear struts.
http://www.stabilus.com/default_e.asp