Amxx Bomb Countdown HUD Timer
With this plugin you can see a Hud with the time of the C4, until it explodes.
If there is less than 8 seconds left to explode, the hudmessage color will be red, if> 7 it will be yellow and> 13 it will be green.
Install amxx plugins :
Put C4timer.amxx in amxmodx / plugins.
Add C4timer.amxx at the bottom of plugins.ini and save it.
Finally change map or restart the server.