OC car audio shops?

Have a custom 8" sub box from Scud Audio, but I'm having a heck of a time finding much info on the speaker wiring in a 488 (Pista if it matters). Without really being 100% sure where to tap a signal from for the amp I'm hesitating on the DIY job. Anybody have shops in OC that are familiar with the 458/488/F8 wiring and interior tricks?

Only info I've seen is about "Kevin" who's presumably not in the OC, and the posts are all generally 5+ years old. I know its a bit taboo to put a sub in a Ferrari (engine being the music and all that), but I'm still surprised just how uncommon it seems to be given the lack of posts about it.