i read people having issues with ASWC on this car. i suggest getting the PAC if you're going to run pioneer on the base Z, unless ofcourse, bigaudiofanat can explain what people need to do to make the ASWC work on this car.
i had on issue running pioneer HU with ASWC on my honda though.
it was literally tap remote wire, plug it in, and walla.
been running PAC on my pioneers on my Z for 4yrs. no issue.