street racing, then 10.0 : 1 is not a bad AFR. If you want to dyno or drag and make separate pulls with time to cool down in between runs then leaner would be okay. The stock ecu is actually very good for big turbos, high boost, and large injectors. The JWT mapping has 10.0 to 1 sections so it sounds like it is working well. The Technosports 1000awhp R33 GTR runs a modified stock ecu. They used to run a HKS F-Con Vpro but dumped it for the stock ecu. They have 6x1000cc mians, twin IHI RX6 bb turbos and are boosting 2.2 bar (about 34psi).