Something else to think about with regard to the Mitsubishis, they tended to use the same engine (or form factor) across their model line, which means there are probably more engine upgrade options than most.
The 2.6L Astron 4-banger was used in the Starion/Conquest, which opens up fuel injection and turbocharging options. Since the StarQuest community also got the venerable 4G63T Sirius engine in some markets, which is also found in the Eclipse/Talon/Laser AND every Lanver Evolution rally car for 9 generations, there is plenty of tech out there regarding engine swaps to the smaller, more capable 2.0L. (People are making over 1200 *wheel* horsepower on these engines today. 300hp is maybe a US$1500 project.)
On top of that, a lot of people in the 4G63 community ditch the 2.0 for the 2.4 bottom end. We tend to mix-and-match. 2.0 crank in a 2.4, 2.4 crank in a 2.0. Stoked, de-stroked. All been done and just a Google away, really. And, when you think about how the 4D55 and 4D56 turbo diesels are pretty much a direct bolt-on (as far as I know), there's a lot of OEM quality engine swap options for whatever powerband you're after to consider.
Less familiar to me, but still nice to know and think about, the 6G7X V6 series shares a decent bit of kit with the 3000GT VR4/Dodge Stealth R/T, which was a 300hp, all-wheel drive super cruiser. They have an aftermarket all their own.
Of course, there's always the cognitive dissonance in effect when considering putting three bills into a vehicle you paid less than one for, but it's food for thought.
