05 chopper's not adjustable! I have the same problem and I am 215!! I bought some new shock but they are hieght adjustable only. Have tried them out yet...155lbs @ 55 mph is alot more forces than 155lbs in the driveway. Dont want it too soft or it will bottom out. If your an aggressive ride you'll want the stiffer suspension. also the suspension can be adjusted to your weight and riding style. Just go see your mechanics.
Pro - Let us know how you like the air ride come end of the season. I have been thinking about adding that myself but the local mechanic has been trying to talk me out of it (problems??).just get an airride system...it'll cost ya but it's the best money I've spent...next the XXX carb...then beer