I must say that I like the Fatty's. I bought my Banshee new, 100% stock. Rode it stock for about a year, then installed the Fatty's, K&N, rejetted and I was VERY impressed with the power increase.
That being said, I haven't used any other pipes to compare them with, so I can't say they are better or worse than any others out there. But they are MUCH better than the stockers, that i do know firsthand, lol. I think they are a great all around pipe, I'm very happy with mine.