Click or press space. I'm gonna be honest though, that T444E sounds realistic like, listen to that: https://youtu.be/rUfx8PKFEZU (Normally, I don't like those Photon buses, just to be completely honest, but the 3800's with a T444E engine, I actually like, cuz the others, I don't really like the way the engines sound, but the 3800's with a T444E sound realistic and actually good imo.) And yes, I love this engine a lot, as you can probably tell. lol