Honda HA-420 light business jet - video

[Frank S]

Well, that's not much/any worse than when they sling them under the wings. They are closer to the fuselage, but the pylons are also taller. I'm sure, though, that it all went into the aerodynamic soup-pot they used to squeeze every bit of performance this thing. It sure ain't your daddy's Civic!

They obviously had to mount the engines somewhere. Mounting them forward and under the wings on such a small air frame would have created a host of different problems, the wings would have had to be mounted higher off the ground for one, this would have meant either a much taller profile to the aircraft and greatly altering the design and weight of the fuselage just for starters, or much taller landing gear mounting adding more weight and difficulty in the ability to stow the gear away in flight.
Shorter high mounted pods on top of the wings either forward mounting or to the rear may have been an option though at the cost of noise in the cabin for one.
So many things involving the aeronautics of an aircraft must be considered when designing, and Honda has a reputation of figuring things out, though not always on the first go round