I used to do stuff like this myself but don't have the time these day and had a shop do it. It was $100 which for me was well worth it. Having said that it's definitely a do it your self project. Topspeed did offer a 986forum discount and I ended up get mine for $160 shipped. You may what to ask about it when you order it. Like the pulley this mod does not make a huge difference. A little more ho and a little throatier exhaust sound.
Hey, I just saw your post on Top Speed cat delete pipes for $200.
That's a good deal and was thinking of doing that for the coming Autocross and PCA DEs.
Do you think it is a DIY? I have a lot of tools, but no torch.