littlepig, that figure is pretty meaningless on its own. You might well have 2.5 + bar static pressure, but your flow rate might still be far too low for that shower. they might possibly mean that you must have 2.5 bar pressure at shower when its running, but you need to know flow rate through shower to begin to make sense of that. In general combi boilers will only work with normal shower valves running at up to 15 litres/min.
Edit 9.56 pm. - Just looked at your proposed set up. Forget it.
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