You should be able to lower the maximum brew pressure by adjusting the OPV and testing with a blind basket.

Generally it's not a good idea to let pressures rise above 10 bars, because a phase of puck compression happens at around 10.5 bars that will slow the flow and make the pressures rise even higher. It's also likely that your puck will channel with these higher pressures. Setting your OPV to around 9.5 bars allows you to grind finer to adjust flow, and hence flavour, without creating a huge pressure peak. Don't grind coarser as this will decrease extraction and your shots sound like they're already flowing pretty fast. Don't raise the dose because this will have the same effect on flow as grinding finer, but it will decrease extraction.