Hi there is a firm in the United Kingdom that change the headlights, front bumper, both side wings and spray to match the car for around £2100 which isnt that bad really.
the boxster rs is a one off but ruff would proberly do it for you.. remember this guys took his 03 boxster from the showroom to the workshop and changed EVERYTHING.. engine, springs you name it he changed it.. here is the complete installation guide:
Mickymouse, i will post some pics of the bumper i have but to give you an idea its the same as above but will take the boxster shape headlights..
there is also alot of firms in the United States that do this upgrade to the 996 look. I will get the website from my other computer and post it here..
link1
check this picture out:
http://www.ramis-porsche.com/pics/PSI/PSI_intro03.jpg
here is the guide:
this is his car before the conversion a brand new boxster s
stage 1 stage 2 stage 3 stage 4 stage 5 stage 6 final stage complete delivery day