Keep in mind that Honda's warranty verbiage is clear about modifications voiding warranties. It is especially so with extended warranties. They could, if the dealer informed them of the mod, use it to tell you to pound sound (legal def: **** off round eye!) with regards to your warranty.
That being said...if you keep records and receipts showing you followed or exceeded Hondas maintenance schedules, and if you keep the OEM master and slave, you just re-install it before taking it to the dealership. The records are important because if you never take your car to the dealership, which you should do if you are planning on mods, you gotta show proof you followed the maint. sched.
The miles left on the extend is what would make the decision for me. Close to the end? Screw it, play away. Otherwise go ahead and buy the shite you want to add to the car and install after extend is dead.
In the immortal words of Slim Shady: "Be smart. Dont be a retart". ...