I owned a Jap Spec VII. They do come mapped for higher octane fuel and knock a fair bit even on 98, they came with the speedo limiter set also (both easy fixes with software download a some knowledge on maps).

They were never released here in Oz so insurance wasnt an issue. HID's are in them but are supposed to be removed for compliance here but mine had them in still.

Think that was all off the top of my head. Great cars, just buy as well as you can and if its cheap, its for a reason