Ditto.
How many miles have you driven it, how's the oil look, and what maintenance has been done in the last couple of years?
Replacing any EFI engine is tough due to the programming. Changing any significant air flow items will not work well with stock programming, and most people don't want to pay to get custom tuning, the device required, etc. So staying right at stock is the best way, unless you have the time and will put in the effort to do much more.
I think there is a safe 40hp to gain by altering the compression and doing a full bigger exhaust, and custom tuning, with custom camshaft, the special valve springs etc. But nobody yet to date has done all of those things together, thus the result is a random 25hp gain, and with great difficulty installing super high dollar small headers.
Try to fix the existing engine issue, keep it well maintained, and engine it as it is. Everything beyond that gets very complicated, given the tight engine bay, and horrible exhaust manifolds.
