So just a random question but my KF doesn't have any EGR system at all. The holes are there for it on the intake plenum, but havn't been drilled all the way through. Just wondering if there's any effect of having one vs not. Just seems kind of strange that mitsubishi made this model with the capacity to have EGR but not actually fit it. Was it something that only become mandatory after 1998 and they knew they'd have to fit it at some point during the cars manufacturing life?

Overseas models had EGR from inception of the model hence why the provision is there.
From what I gather, EGR will decrease emissions (the reason it is used) and reduce fuel consumption minimally.
I think in the life of the car you will not redeem enough fuel savings to cover the cost of installation.

I wasn't aware of the fuel savings, interesting. Basically the EGR system is designed to slightly lower the temperature of the air/fuel burn in the cylinders at certain times which reduces the amount of smog-producing oxides of nitrogen that's created. It does this by introducing a small amount of exhaust gas into the plenum at times when the slight drop in power this causes isn't noticeable, such as during deceleration. It's part of the emissions control system, prior to the TH/TJ the rules in Oz didn't require it I guess. No real point in retro-fitting it unless you're deeply, deeply green, in which case a bicycle or horse is probably a better option.