[Gary]

Hey Luyi, welcome.
I have a little experience w Akrapovic on my '13 GT. I have alot of fun with mine. Somedays I put it in and somedays its left out. Its great to be able to play around with dB killer.
I will say putting a smear of anti-seize on the insert face makes it very easy to take off when ya wanna have some fun with noise.
I also installed Arrow header to eliminate the cat. An added bonus to that is left cyclinder now runs much cooler, according to my laser thermometer. Now same temp as right cyclinder. PLUS the wonderful pulse of our 360degree twin.
You can rely on what Mark and Raul have to advise.