I'm not clear what you mean by "whole exhaust system" ? If all you are changing is how you handle the exhaust gases (i.e.more open pipes) then a PC is probably not required. But on these FI bikes if you open up the air input via Thunder Kit etc -you need to also adjust the fuel input and on a FI bike that is most easily done with a PC....why if i modify the pipes of a motorcycle the bike will be fine, BUT
IF i modifie the whole exahust sistem, i will requiere a power comander?..
i ve seen some bikes messed up because they modified the whole exhaust sistem, but twhe u modifie just the pipe seems to run ok...
Did that answer your query ?