a buddy of mine has some trd springs and struts on his 01 is300. now the struts are leaking and he was wondering if he could use different struts with the trd springs like some bilsteins...... is this possible or is this one of those set-ups where the springs must be complete with those exact struts?

 

There should be no trouble switching out the shocks for a different set. What makes the TRD special is the name and the design for the car, but other companies make performance shocks for the car as well. He should be fine.