I have ran both T5's and T6's on my Banshee. The T5's hit harder on the top, the T6's have a lot more mid range and similar power up top. My banshee is not ported. One thing I really like about the T6's is the mounting is a huge improvement over the T5's.
I called Toomey about the T6's and ported motors, he said they don't work well with ported motors. So, when my motor goes I guess my T6's will also go away because I'm getting the Cheeta Cubs. I'm gonna miss the quality of the T6's, they are awesome pipes for stock ports.