If you have alot of hard miles on the shocks might as well do both, it will save you money and time in the long run. But if you don't have hard miles on them and you just had the luck of having a bad shock you can get away with only changing the one.
Tried searching but couldn't find an answer. I have a blown rear shock, should I replace both sides or will I be ok just replacing the one side?
There isn't any hard and fast rule that says that you should replace shocks in pairs. Then again, shocks aren't supposed to blow/leak. General rule of thumb is you want the car properly damped at all 4 corners. If the other shocks are in danger of blowing, replace them. If not, leave them (unless you like throwing away money).
It would be a good idea on your part to determine why one of your shocks blew, though (and not the others). Or else you run the risk of paying for more new shocks to replace more blown shocks because you never solved the cause of the problem.
I think my problem was that I over tightened it. I was trying to tightening it full hard at autox and I twisted right through the stop. Something must of stripped internally.
My coilovers are Ksports which seem to have a reputation for blowing.
The shocks are only 120 shipped. They would rebuild for that price but I didn't want to wait for the coilovers to be shipped back to me. A shop should be able to put the spring back on for 50 dollars or less.