By far the most impactful and popular upgrade you can make is switching to carbon wheels. The cheapest and best value entry level wheelset is the Bontrager Aeolus Elite, available in 35mm and 50mm variants.
You have a choice to prioritise snappy acceleration and maximise handling in all wind conditions with the 35mm version or you can choose the faster more aerodynamic 50mm version.
Both versions are covered by Bontragers 2 year, no quibble, FREE crash repair or replacement policy.
The front wheel is €449, the rear is €549.
The wheels are TLR (Tubeless ready) so they can be set up either with tubes or tubeless