Clicking sounds in the back when accelerating powerfully

Hello, Just bought a GTR Carbon

it goes too fast for me to push all the way yet

but is it normal when i accelerate powerfully in GTR mode or Pro, to hear a sound in the back? it doesn’t make that clicking sound when i gather speed though? it s really in the first 2 meters?
It s the same sound when i break as well?
thx for your answer

 

Check tension on your drive belts. Should only be 5mm play.