Weird Sound no Power

[begeta50]

I was driving my car, and weird sound started to the point that got loud and the car has no power. The car engine runs but the sound is there all the time even if engine is at idle. I took it to a shop and the mechanic says that I need a new transmission.
The sound is similar or like when the muffler is broken.

[Patate]

have you check the coilpacks

[BluechipS4]

what are coil packs?