(i)as respects remuneration, whether in respect of business already procured or in respect of business to be procured thereafter, be such as may be mutually agreed upon between the parties, subject, in the case of remuneration payable on business procured before such commencement, to a maximum of an over-riding commission of two and a half per cent, plus a further commission not exceeding three and three-quarter per cent, on premiums in respect of which no commission is payable to any insurance agent;