Had one of these on the Zed for over 2 years now as my fuel gauge (float) is wildly pessimistic, it's very accurate for fuel consumption, miles to empty, also good for air intake temp, water temp etc.
It is common for paints to look a very slightly different shade when sprayed on plastic as opposed to metal but that does look unusually mis matched. Sorry I can't be more helpful
It wasn't too bad, had to move some AC piping on the nerarside and the radiator expansion bottle needs to come out too, I expect you will have a lot more hardware to mvoe as it comes out from the top.
A little update, fitted the Mishimoto on Thursday last week, see Page 24 of my build thread here :- http://www.350z-uk.com/topic/58750-how-to-smurfadise-a-zedbrembos-p20/page__st__460
These used to be supplied from Mishimoto with just the cables from the two fans and no connectors. Good news, they are now supplied with Nissan connectors and plug straight into the Nissan loom .