If you want to keep your stock mirrors, go to
www.koubalink.com. Scroll down the left side till you come to OTHER PRODUCTS, then click on Suzuki DualSport 2" mirror extenders. I put these on my 2005 and what a difference. The best $25.00 I ever spent. These fit all 10mm x 1.25 mm threads, which is what the Boulevards have.
You need to be careful as some of your aftermarket mirrors are plastic and they vibrate very bad (no weight )and they don't last.
Brad in WV. 2005 with mild carb work & Harley Dyna Muffler