I just turned in my leased 2002 Honda S2000. I had a 4yr lease and bought it straight from the dealer. I upgraded the center console and one of the cover plates to the new 2004 interior. I also put in a killer sound system replacing all the speakers and head unit.

The inspector told me to talk to the dealer and and my leasing company.

I spoke with them and they said they would charge me to re-install the stock stereo/speakers and center console/cover plate. I was told the leased vehicle needs to be returned in the exact same manner as it was leased. IE, I leased it with sport racing tires so it had to have sport racing tires when it was returned, etc...

I had everything returned to stock prior to returning it and never had an issue after that. Hope this info helps.