I'm pretty sure the instrument cluster and center counsel garnishes are not leather but a synthetic material. The steering wheel is promoted as leather-trimmed and a standard luxury feature, but there is no mention of the other surface materials as leather in marketing information. I've also looked at the garnish materials while removed, using 60 power magnification, and they look to be very thin synthetic material backed with approximately an eighth inch of foam.The only leather is see with my NuLuxe interior is as you said the steering wheel, and over the instrument cluster and the sides of the center console. Interested in your comment however, because I'm taking my 2 month old CT200H premium into a custom interior shop to replace all of the NuLuxe on the seats with genuine leather. I found them unacceptably hot in the NC summer. Spoiled I guess from living with leather seating in every car I've owned for a long long time. The only way I would have kept my vinyl (NuLuxe) seats if if I lived at the beach and wanted to jump in the car with wet bathing suits every day.
Steps to upgrade sound system (1) get amp and use with OEM speakers (2) replace OEM speakers, The sub is superfluous unless you like vibrations for low frequencies less than 100 Hz. You can improve low end frequencies by adding some replacement co-axial or tri-axial speakers for the two front door speakers.Wow...very technical post...thank you....they fooled me on the trim pieces with the white stitching. I take the car in tomorrow and probably get it back Friday for the leather redo. I have them perforating the center sections of the seats to look more Lexus like and adding white stitching to match the other details. I will post some pics when I get the car back. I'm having them add a larger sub woofer and an amp at the same time based upon other posts I've read about the effectiveness of this upgrade for the Premium Sound system.