I just tested this in the scenario editor:
Mangonels take out a town center with 2400 HP in around 52 seconds, corresponding to a damage output per minute of about 2800 per minute.
Rams need 97 seconds to take out town centers. This equals a damage output against town centers of roughly 1500 per minute.
Previously the damage output of mangonels against tcs used to be around 750 per minute, as is mentioned in here:
While the damage output of rams against town centers did not change, the damage output of mangonels against town centers is now four times as high as it used to be.
Town centers have 2400 HP.
A single pertard on the current build 34699 does a damage of 1560 to a town center.
In the HD edition, a petard caused 520 damage to a towncenter.
In other words, petards now do three times the damage to town centers than previosuly.
I didn’t see it happen, but I was in a 2v2 on discord with a friend and he suddenly was shocked as he reported he had destroyed an enemy TC with only 2 bombard cannon shots. I said the TC was probably already weak, but now seeing this report it rings a bell.