Bridgend Athletic, who sit in second and have a game in hand, recorded the bonus point that evaded Builth Wells, putting six tries past third placed Loughor in a 37-15 victory.
Kidwelly went two better at bottom placed Gorseinon, hitting eight in a 60-14 demolition job.
Division Three West leaders Pontyberem were even narrower winners than their Two West counterparts, squeaking to a
13-11 victory at Crymych in a third v first clash.
This allowed second place Aberystwyth to reduce Pontyberem's lead at the top to four points after their bonus point win at local rivals Lampeter Town, where they scored four tries in a 36-17 win.
Aberavon Quins also scored four tries on their travels, as the Division Three South West leaders won 33-8 at Maesteg Celtic.
Like Quins, second place Tondu recorded four tries and 33 points away from home - but their winning margin was vastly different to that of the club they now sit nine points behind.
The Waterwheelers edged out third place Glynneath 33-32 in an eight-try thriller, with the hosts picking up two losing bonus points at Abernant Park.
Llandeilo, the table toppers in Division Four West, posted an astonishing 11 tries in a 70-0 route at Pembroke, while Division Four South West leaders Bryncoch ran in seven in a 41-24 victory at Aberavon Green Stars.