Looks interesting! A genuine 3'' system for proper cheap!
are the boxes 100% straight through? or are they baffled?
I once bought a '2.5 inch' system, and had to cut it up to modify, and found that whilst the pipes and inlets to the boxes were 2.5, the run through the box was only 2''! Complete joke.
if these are a genuine straight through system I might be tempted to try one!