I'm trying to source all the parts for the OEM park pilot.

I've read some threads that suggest I need a speaker, I thought the beeps would go through the centre speaker in the dash. Is this correct?
There was also some mention of a cable loom in the roof lining.

If I need to install a new speaker, I might as well go for the fleabay option.

I like the OEM route to keep it standard, but is the OEM too expensive and too difficult?

Opinions welcome.