Join Date: Apr 2008
Location: Mentor, OH
Thanked 75 Times in 51 Posts
Lots of people have dyno'd before and afters. The thing to note is that the header alone isn't going to net you any big gains. But as part of a system where you'd also replace the muffler with an aftermarket one, and a tune so that your bike knows how to utilize it's free flowing exhaust, I think 8-10 hp is pretty standard. In comparison, a full Arrow titanium race exhaust on my '12 netted 13 hp.
And I'm not sure about the weight difference. It does save some weight, more so on the 06-12 vs the 13+. On the 06-12 I'm removing the cat and exup, on a 13+ it's only the cat. The exup.is part of the mid-pipe and gets removed with most slip-ons. If I can find a small scale, I'll weigh them before/after and post the results.