A customer emailed to ask Remotes Unlimited what the correct replacement remote is for a 2005 Acura RSX. Acura used the same keyless entry system on vehicles for the 2002 through 2006 model years. The replacement remote transmitter for this system is Remotes Unlimited part 640-1640. This keyfob is a 3-button remote with FCC ID OUCG8D-355H-A and Acura part number 72147-S6M-A01 or 72147-S6M-A02. See the remote at this link.
The keyless entry modules in 2002-2006 Acura RSX vehicles that use this remote are user programmable. Remotes Unlimited provides free programming instructions and phone technical support with each purchased part.