I really don’t think that’s why you can hear 92.5 further to the north than 104.5. You can still hear the 92.5 in KWUP’s weak coverage. You lose 104.5 before KZCW starts to come in.104.5 has a cochannel in Beaumont that is easily picked up in Houston when Beaumont is off the air. 92.5 also shares their channel with stations in Beaumont and Bay City, but these are rarily heard in Houston. Height plus a clear channel make the difference.