I've done it to all 3 of the hyper 21 engines I've had.
It increases the performace if anything.
I don't know what that "Turbo" fan is designed for, but my engine all seamed to run better without it.

You can leave the pull start on if you want, and still use the statrter box

The box you're looking at is really better for 1/10th scale cars and truck, But many guys use them without problems after an engine is broken in. I prefer to use the Ofna "True start" box for my 1/8th scales and Monster trucks that use .21s. You'll find that smaller box difficult to use when breaking in a new .21 size engine.

Good luck