Like most mods to the 2.5L, dont expect HUGE differences... It helps, and in my opinion, its one of the easiest mods that gives the most bang for the buck, but again, its not something you will feel while driving off the line (in my case, the difference was felt more when driving down the highway, where before I would need to downshift, the motor can handle the small hills in the same gear; but then again, I not only have the TB and Spacer, but plenty of other mods like the e-Fan, 19# injectors, improved ignition with difer plugs gaps, etc.).
So if you ask me, is it worth it? Yes, it is, and I recommend you do it! Will it make a drastic difference? No, you would be disappointed if you expect that...
Felipe