tail pipe has to be o rings on the injectors or tuned to a different size injector. For example running 370 injectors with a 550 tune. O2 Sensors. Coolant temp sensor.Clogged air filters.
Your leak can be power steering leak from the pump, hoses or cam seals, or leaking VTC sprockets.
Fan can be your coolant temp sensor also..good luck. If we were closer I might be able to help you.