In Cambridge Engineering, Inc. v. Mercury Partners they found that the non-compete clause was so broad as to keep the employee from finding reasonable work, so it was thrown out. In this case, you signed the non-compete agreement while your company was performing A, now they want to perform B which is something you do on the side. My guess would be that in order to enforce B they would need you to sign a whole new NCA. I would check with a lawyer though.