Actually, there are many bows that will shoot a 400 grain arrow at 297 with a 30" /70.

My Pat Dually at 29" , 71 pounds shot a 400 grain arrow at 294. And also did it with almost an inch and half more brace height. W/ a 30" draw it would likely be in the mid 3-singles.

My Hoyt CyberTec (Same brace height as your LX) shot a 400 grain arrow at 290 FPS. Again 29" draw, 71 pounds. A 30" Draw bow would put it at least 297 FPS and probably more.

While the LX IS a fast bow, there are plenty of designs that will do that these days.

Now what was that about a pipe?