i had read that the only difference was auditory but only the 3.4L was mentioned specifically I think. If you got the materials and the skills than why not eh? i'm interested to see how it works out for you, i've got the 3RZ also.
I have one on my 03 2.7, I have had it on for about 10,000 miles and paid the $79 or so for it. I also have the k&n set up so that might make a difference, as for the TBS to me there is no noticable difference in horse power and mpg but a little quicker throttle response. Worth the money, well if you have the money to spend why not. If you build it thats even better.