I have a Yosh on my '03 636 and I love it. Looks great and sounds good, not the loudest I have heard. I can not believe the power increase on take-off! But I would realy love to have an Akrapovic full system.
I have a Two-brothers. I debated getting a Akro but I just couldn't spend the money for a pipe that just doesn't work any better than other pipes. People just want it because its the one used on Kawasaki's race team. But remember every pipe on Kawasaki's race team bikes is hand made for that bike to maximize its potential.
i had a zx6rr 2003 , i went with micron 2 tone high mount it sounds good & looks great. to many bikes have the same pipes.so i went with micron easy to bolt on. when i pulled up it cacht everybody eye, not to brag but it look nice.