Am I being a little optimistic with this car???
IMHO ... just a tad !!!!

It weighs a lot, around 1.7 tonnes, so the power to weight ratio is never going to be that good, regardless of mods. It was built as a long range executive cruiser, not a boy-racer go faster machine.
Induction kit will increase the noise and do nothing for the performance .. except make it worse .... engines like lots of cold air (high mass NOT volume) .. an induction kit will give you engine bay warm air .. and probably less volume .. so a lot less mass .. so the ECU will cut the fuel to maintain the fuel air ratio (by MASS) ... down goes the performance ...
Exhaust is pretty free flowing for most of its length already .. its the exhaust manifolds that need work .. and that won't be cheap
Cams can be changed for longer duration .. 3.0ltr cams in a 2.5 is a common upgrade .. but for the 2.0 I'm not sure whats available.
The rest of your mods are cosmetic not performance, so unless you strip out a lot of weight .. and I mean a LOT .... your are not going to greatly enhance things.
Now the 3.2 V6 .... even without any work ... is a much nicer engine .... but I'm biased .... a tad ..
