I would service it front to back and have the oil sampled before doing anything. If the motor is already about to **** the bed, it should show up in the oil analysis.
From there all depends on budget. If tight, just do the pipe, maybe a used SCT, a cold air intake, and blockoff plates for the EGR.
I ran a 500hp street tune from IDP for years on a stock air intake (with pipe, EGR plates, and SCT) while I was under warranty. A real high flow intake will really help top end power and should drop EGTs. Highest flowing is the 'No Limit' setup. I sucked in the filter miner on my AFE kit once I stepped up to a 'Hot Street' tune...stock turbochargers, most all air mods.
100% buy a monitor to check engine vitals. I am not keen on using my tuner for it due to the cost of it, in the event some prick breaks in to steal it. Used Edge CS are pretty cheap now that the V2 are all out now.