2 cts' or less worth
1)Insulation Piping Class 1 or 0-
Oops, don't know any much better but my aircon cousin told me black insulation piping is better than grey -
Well, I needed to buy another set of air-con for another flat - same , Toshiba, made in Thailand. I finally bought from Gain City which my aircon supervisor originally advised- I paid $150 more than at Carre4- price of peace of mind
At Gain City, they have other thicker insulations but cost more, they will advise you.
For me, I just took the black piping vs the grey piping when they ask me to select for normal installation.
2) Drainage pipe - bigger better, but cost more?
Less pipe joints - so less problem at joints.
3) Ask for experienced installer & then pray.