Hey man, truck looks great, love the facelift sport package!
For plugs, I recommend OEM NGK plugs I just did mine last year. Coil packs I wouldn't replace unless they are misfiring, they aren't really a maintenance item.
As long as the fluids are fresh and other maintenance taken care of, drive the piss out of it!
For speakers, I would go to
www.bavsound.com as they make great speakers for our E53's
AS well, we are rounding up 10 buyers for the first round of reproduced decorative skid plates, see the thread started by Clockwork, painted in Titan Silver it would be a HANDSOME piece on the front of your X