Except with a good map on a PC you'll see the most improvement between 4500 and 6000rpm, right where the emissions "hic-up" in the fuel-air curve is.

I've seen bone stock 600RR's gain 4-5 HP in the 4500 - 6000 range with a just a PC and a good custom map.

 

i just ordered a yosh pipe last week and had all the same questions, i called the only thee places in my area that offer dyno services and all three said it is only necessary for a full system or if i plan on reving the engine past 8000 most of the time (i found this advice quite honest considering they could have made a sale.....they must love riding too.

 

I would never put a yosh on my bike unless I don't have much money.If you do your research akropovick/arata make the best hands down full exhaust systems for your honda

 

It is common knowledge that:
Yoshimura, 2 Brothers, Morikawi, Sato, Akrapovik, and Arata
are the leaders in full and slipon systems when it comes to engineering
ANDbuild quality.
The problem with the last three brands, is that they are overpriced.

 

I think what he means is that Yoshimura usually works with Suzuki where as Akrapovic and Moriwaki have long running relationships with HRC (Moriwaki headquarters is across the street from SuzukaCircuit, Honda's race track).