Macpherson struts are indeed stock shocks on the GTS, these don't sound like your every day regular car struts, are they performance based struts? And if so doesn't that mean they can handle some performance springs, lets say Tein S.Tech or Eibach pro or Hotchkis?
I've heard of other people running lower/performance springs on their stock struts/shocks for over a year and not noticing any problems or excessive wear.
I am inquiring about this or purposing this theory so that perhaps one can save money and not have to buy aftermarket shocks/struts and just slap in some springs to obtain a 1.5" drop and not have to worry about their shocks/struts blowing out sooner than they should.