I like the OEM and Hartge, but you don't often see a Hartge spoiler on a ti, so that might be a better choice if you want to be different.
BTW, where were you planning to get the Hartge spoiler and how much? I'm actually considering that one and the Racing Dynamics spoiler ($185.25 before tax & shipping). It's a bit plain and simple, but clean.
Link to picture of RD spoiler