January 19, 2013 5:11 AM PST
You have a choice of 2 or 4 ohm speakers. They will be 5.25 inch speakers. There are also some out there that run 3 ohm. System is designed for 2 Ohm but you can use 4 Ohm. If you get him 4 Ohm speakers that will reduce to volume, so he wants them louder stick with 2 Ohm speakers. Hogtunes (long warranty), J&M make direct replacement speakers. J&M has an adapter that allows for 6.5 Inch speakers giving you more base. Inexpensive you can look at Rockford Fosgate, JVC even Sony Marine 5.25, all three make Marine grade (waterproof) inexpensive speakers, but they will be 4 Ohm so you may need a larger amplifier to get the same volume.