I am debating on wheather to get the white bros R4 or e series. Which one puts out more power and which one sounds better? thanks

01 black DS

 

I have the E-Series, and it does what a person would expect a DS pipe to do. It adds a good amount of power down low, it's made exceptionally well and the sound isn't obnoxious either. It's louder, but doesn't hurt your ears after a long ride. In tests done on a 400EX, the R4 didn't perform as well as the E-Series, and it was louder. It doesn't prove the same for the DS without any REAL tests, but I like to think I bought the quieter pipe. I'd recomend it to anyone as a good buy. Can't tell you what the R4 is like, I've never experienced it on a DS. The other pipe I think may be a good buy but does cost more is the Custom X Series 2. Though, now that several companies have come out with second and third revisions of their pipes, I've been hearing they are all a good deal better now, which opens the field for you to choose from.