my mate has just done a 3inch turbo back exhaust on my 04 str and he is doin them for $600 suncoast exhaust& mechanic.
http://www.truelocal.com.au/business/suncoast-exhaust-and-mechanical/noosaville
http://www.truelocal.com.au/business/suncoast-exhaust-and-mechanical/noosaville