Rattle From either Exhaust System or Kinda Sounds like Timing Chain Tensioner under load when accelerating?

[Darren Whelan]

When Normally driving Shift Light tell you to up, rattle occurs, if downshifted goes away until next gear needed, no loss of power but i feel just to drive easier,as in not attempt to push the engine, of which iam not(40mph) its bugging me,

 

Edited October 22, 2021 by Darren Whelan
didnt finish text.

[Konrad C]

What engine, petrol or diesel? Since exhaust is mentioned, check the under body shield above the rear silencer or other parts of the exhaust. I had the shield on mine fall and rest on to the rear silencer. The aluminium corroded around the bolt holes. I fixed the shield back in place using large penny washers and some spare pieces of aluminium.

This is only a guess and could be something else, but without more info, it is hard to give a proper diagnosis.