Engine Flush - Worth it? Do It or No?

[chattersking]

During a recent oil change I was offered an "Engine Flush" for $10 extra. According to them it will increase power in my car by cleaning all the gunky old oil and will make my engine perform like new.
I want to ask your honest opinion if I should proceed with this and if it is really worth it or should I just forget it for good.
I understand there is a lot of debate regarding this issue on the internet and the mostly adverse reviews are regarding how it will clog pistons valves on some older engines. However since my engine is pretty new with only 50 thousand kilometres I do not anticipate the same reaction due to this flush based on the information I was reading.

Therefore my question here is specifically limited to how it will affect for our Toyota Yaris engines....

Please advise