If your used to standard sapph you'll never look back, after all they should have been more from the factory but were detuned to 204bhp which nowadays wouldn't see off a diesel and that's just wrong.
Cheap upgrade and won't stress any components engine turbo or other.
You may decide to go stage 3 in years to come but that's when your talking turbo intercooler brakes suspension etc etc on top plus you need a strong engine to start with, you won't regret stage one and try to keep it that way then you can just enjoy the car without spending £££££ every month.