2015 Subaru Impreza FB20 exhaust crackle?

Idk if this is normal, but I have a 2015 Impreza with an FB20 engine, and I installed a Nameless axleback exhaust, and now sometimes if the engine is warmed up, I can get my impreza to crackle a little when I let off throttle, i havent changed anything else about the car other then some cosmetic mods.