I change my string and cable every year. I make my own so it is easier and cheaper for me to do it. Most people seem to change the string every year or two and the cable(s) every couple years. Depends on the care it gets, how much usage, etc. For the price I feel it's cheap insurance to change it more often. Material for your bowstring depends on what you want. Check www.bcyfibers.com and it should help a little. I use 450 Plus (even though fastflight came on my bow) and haven't noticed any problems. For me 450 Plus is the way to go, others may have different opinions. If you have 8 years on your string then IMO you should replace it.