MREV Manifold is really only beneficial on a 296bhp (05/06) car as the inlet manifold is a cr@p design. In essence its a modified 03 plenum that is hugely beneficial in terms of TQ.
Iso Thermal, is really the addition of the lower gasket (between lower plenum and inlet manifold) basically designed to reduce heat transfer and in theory reduce intake temps.
Copper part is a heating replacement for your throttle bodies in very cold climates (not required in the UK)
Best bet is to go for the iso thermal 5/16 kit.
Dan