Because IBU2 only have two sound channel, one for engine, one for other sound effect, no extra channel for overlapping, so you don't hear cannon sound at 8:22 time mark.

Is there a independent reviewer? this bring another question, so called "reviewer" is qualified by whom? form the day one we lunched TK22, IBU2 users judged it in all forums, moderator of rctankregiment even locked our account, because one of their senior member is selling IBU2.