Here is another plugin which tweaks gameplay a bit.
This little plugin simply detonates a grenade when it collides with a player. Like a rocket

You can set it to detonate only rifle grenades, or only frag greandes, or both.
ConVars
dod_detonade_frag_grenades - Whether or not detonate frag grenade when it collides with a player (Default: disabled)
dod_detonade_rifle_grenades - Whether or not detonate rifle grenade when it collides with a player (Default: enabled)
Add those two commands in server.cfg and have fun!