This a good match??
 

Aqua 50 Z pump
Bix pro 3
Swiffy 6002
Maze 4 Gpu (or silverprop if I can source one in UK)
Swiffy poly Bay Res

So are they a good match up or did I go horribly wrong somewhere?? Cheers :)

Sounds like a good setup to me...

Well, I'd save money by not getting a reservoir. It'll improve flow too. But I also wouldn't spend that much on a radiator.

Typically a res will improve flow actually, if positioned correctly in the loop, by reducing the net positive suction head of the system.

Can you elaborate more on this?

True Butcher, but the first thing most users do is stick 1/2" barbs on pump inlet and run a fair bit of 1/2" tubing to the res. I suppose you meant this with "positioned correctly".

Q: Why don't reservoirs come with a 16mm barb to match the eheim 1250 inlet?
A: Because not everyone uses eheim pumps
Q: Why don't all pumps have bigger inlets?
A: Because all fittings, such as reservoirs, are 1/2"

Egg, chicken, egg, chicken (repeat)

PS: Yes, I know about 3/8" stuff, I was making a point.
PPS: I trust we've all seen that 350 inlet mod and its impact?

Well the other (cheaper) option is an MCP350/Laing DDC and mod it :)

By positioned correctly I mean directly mounting the pump to the rad, or using a short, wide-bore connection. Not routing 5 feet of 3/8" ID tube round the case to connect it as people are wont to. :p

Metzen - net positive suction head is basically the amount of pressure on the suction side of the pump. If this is too high it can affect the performance of the pump (particularly with the aquarium pumps we use) and cause caviatation. Adding a res reduces pressure as it's a lot easier to pull water from a big open tank than down a thin pipe.

Cavitation is where the pressure in a fluid falls to vapour pressure, therby instantaneously turning the liquid into its vapour form and forming bubbles. Typically the noise you hear isn't the bubbles forming, its when the pressure comes back to VP and these same bubbles collapse in on themselves with a bang. If you get bubbles forming near the leading edge of a lifting surface then the liquid does not flow over the aerofoil as it is supposed too, it just makes streams of bubbles in the liquid and makes minimal lift. Aerofoil doesn't work and so the propellor doesn't work. Often occurs with outboard motors when the leading edges of the propellor gets damaged, by dings, gouges, dents etc.
Same theory will apply to impellers in a centrifugal pump. Too much restriction on the inlet side, as Butcher said, and the pressure at the inlet side of the impeller drops as the pump is having to 'suck' liquid in.
Having a res on the inlet of the pump reduces as much as possible the restriction on the inlet, but may slightly increase total loop restriction depending on its design.

Not sure about Net Postive Suction Head. Thought it was a good thing, as my understanding of it was that the Suction pressure was Net Positive, ie above VP, so reducing the likelyhood of cavitation occurring. Thought zero positive suction head was where bubbles start forming and as pressure on the inlet side falls below NPSH you get more and more bubbles forming.

Sorry, my statements are rather unclear and misleading. :(
It should read - a res will increase the NPSHA which will mean the pump is working less hard (and that's a big deal for centrifugal pumps which don't deliver much pressure to sart with) and reduce the chances of cavitation.
In laymans terms - it's easier to suck water from a res than down a tube. ;)