Originally posted by EliteAccord
Do it yourself is the best and most satisfying way. Just get tools, PB, WD40 or Liquid Wrench, and some High temp antiseize, and a friend or two. 
word...
took me a while to get the header on myself. took me a couple hrs to get the catback on w/ a couple of buddies. the high flow cat depends if its a bolt-on or a weld in type. a muffler shop should be able to install everything for you for around $50-100. much better to do it yourself.