Well guys sorry to bust everyones bubble but i have the "butterfly" mod done and its about the only mod that i can say i've ACTUALLY felt a difference with.
Yeah on my K6 it had a cat. When i installed my micron slip-on it a srt8 pipe. I felt the difference. And notice the bike felt slower when i put the stock 1 back on. I called micron and the guy told me that in R&D the slip on made 3hp. Not sure if thats true. But i know no cat = free flowing. The stock pipe weight about 20lbs, the micron weight 6lbs. Dont u think shaving off lbs makes the bike a lil faster???? Correct me if i'm wrong.It's not necessarily smoother airflow but higher velocity you want. To get higher velocity generally the airflow must be smooth. Anything sitting in the way of airflow takes away power. Everything in the way of the air getting into your intake is a restriction. Every bend no matter how small is a restriction.