i think it would be really cool if Garrys mod would get cool effects for the Noclip mode.
since the character is flying i think it would be cool if when you boost there could be like a warpy zoom line effect around your character to simulate quick speed. also maybe a faint zoom sound effect.
when the character boosts while in no clip near the ground it would be cool if they generated a dist trail on the ground. like it could kick up dirt, water, sand, dust etc. and it would get gradually larger as you near the surface. also maybe some sound effects for that too.
when your character passes through walls or surfaces while in Noclip it could create an effect along the surface of the object (similar to the wave/ripple effect when you touch water). and again mabe some warpy sound effects.
these are just some simple ideas i had. thought it make it seem cooler and more like an ability that just a glitch.