I've heard nothing but good things about Fast Intentions. I've only heard one FI setup though, the FI LTH paired with the FI 12" resonated CBE. There was drone between 2k and 2.5k RPMs. In my 7AT I'm right at 2.5k RPM when on the interstate so I am afraid it will be an issue.
I ended up choosing the Motordyne E370 CBE. It utilizes side branch resonators to remove any drone and rasp but sounds amazing at WOT.
Here is my favorite YouTube video of the exhaust:
http://youtu.be/qhM5y72uo7s
The price is not one of its strong suits however.
If you're not worried about power gains and are looking mostly for sound, hold off on the G3s and put the extra money on an exhaust should you find one you like that is more expensive.