There's not much in it really, the "group a" 044 pump has a higher lockout pressure that's the main difference, something that is never needed on a cossie anyway, as it locks out at 11.2 bar, power consumption is very similar to the std 941 pump, the 044 uses(at lockout) 18amps at 12 volts so less obviously with more voltage of around 12.8-13.4 that they normally run.
2mm thinwall is plenty, this carries 25 amps CONTINUOUSLY, you could use 3mm thinwall but this is roughly 50% more cost and it's not needed, this(3mm) will carry 33 amps continuously, 6mm is way ott, and serves no purpose other than emptying ones wallet quicker, as it's roughly 2 1/2 times the price of 2mm and not needed, it carries 50 amps continuously.
Don't forget a fuse right next to the battery as a certain persons supplied looms rather horrifyingly didn't have this, so a short on the run between the battery and the relay/pump could have destroyed your car by fire, it's a stupid schoolboy error, and not impressive.
tabetha