puting a turbo on a 1.9 EFI HO motor question

I put a Turbo on my sandrail it has a ford 1988 1.9 FI Ho motor in it. I installed a FAST computer on it, put a better fuel pump on it with a braided fuel lines, I aslo put a air to air intercooler on it. The turbo puts out 10-11 lb of boost. I made my 1st trip to the dunes this past weekend and it ran for 2 days and then it cracked a piston. just cracked the very top of it about a 1 inch peice. I have talked to a few other people and I have been told that I needed to run 110 octaine in it (I ran 93) and put better pistons in it. DO you agree with that? the pistons I had were the stock pistons. Do I need to have someone build me a set of pistons and RODs of just pistons. please give me some input for I dont want to have to pull the motor again this summer of ever..