If you look at the chart in the following post, it clearly shows that the SL55 pump has plenty of capacity (with stock injectors). In fact you can run as much as 90-100 psi (if you could adjust the FPR this high) and the pump will still keep up:

https://www.crossfireforum.org/forum...el-system.html

That being said, I think the lean issue (edit: if you have an upgraded pump) lies with the ECM not commanding enough injector duty cycle, until I see some logs which prove me wrong.