Change exhaust need retune ??

[YEN96]

Hi guys, like to check if necessary to retune after changing exhaust.
Running power FC, basically change whole exhaust from header to muffler.
Necessary for retune?? Rpm now like idling also change after change exhaust.

 

[kUmUcHaI 11/1]

Mine hondata k100 on k20a.
Front till end muffler. Didn't send for tuning again. No time. Car run like usual for 2yr.