2005 Acura TL 6Speed. While accelerating there is no noise. However, if slowing down, or foot off gas pedal, while in gear, there is a knocking noise, If the clutch is engaged, and slowing down, there is no knocking noise.
Update: Yes, when the clutch is pushed in, and coasting, there is no noise. If for example, in 3rd gear cruising along, then take foot off gas, it will make the noise.

 

**UPDATE**

My car is lowered btw. I raised my car a tad bit because of my new wheel setup and the knocking noise went away. So thats weird. maybe less stress on axles?

 

The lowered cars have experienced worn CV joints just because of the unusual angle of the half shafts. Many will find the inner joint wears.