Assuming that Citi allows this particular product change, you can simply call and request it. They usually do not do a hard pull, but you should confirm with the rep before starting the process. Once initiated, you typically receive the new card fairly soon (within 2 weeks or so), but the product change officially takes a bit longer (51 days as I recall). You'll get to use the new card and its benefits in the interim, but the change does not officially happen until the 51 days are up. Apparently, if you change your mind, they can un-do the PC in that 51-day period.