Dave,Picture the open end of a piece of pipe. Now air likes to flow along surface walls. By giving a rounded lead in,to the pipes inside edge,entry point,it helps the air flow smoothly into the pipe. Less turbulence equals better air flow. I used my high speed air grinder,a Dremel will do,with a carbide burr,to radius the edge.
<font size=-1>[ This Message was edited by: Mus408 on 2001-07-12 21:22 ]</font>