Well I thought some people here may find this usefull if they buy anything new and the instructions are in Japanese or used and there is no instructions.
http://www.apexi-usa.com/support_installation.asp
All the manual’s are free to download and are in a PDF format so you will need Adobe.
Cheers 
It sucks! it doesn’t tell me which ECU pin to wire to for my turbo timer A/F Reading gauge
Stupid Apexi…
Well I haven’t looked in to anything for the 350z’s and if Fairlady isn’t there, then I’m thinking you would wire that to your MAF wire going to the ecu. Thats the main signal wire for your a/f’s, so it stands to reason you would use it.
Don’t quote me on any of this as I am not 100% positive but it does make sense based on what you stated.
Good luck with it bro and sorry the guides didn’t help ya.
Sweet!!! I actually needed this.
Thanks.