Nissan/Infiniti SE-R, 200SX, 240SX,
and G20
                The classic SE-R, which is overlooked sometimes, is one of the most potent, good handling, FWD cars ever made. It (and the Integra Type R) has been said to be one of the very rare FWD cars that do not understeer. It came with a naturally aspirated 2.0 liter four cylinder making 140HP (a.k.a. the SR20), which was connected to a five speed manual. So it doesn?t sound like much, but the engine was designed ground up to be turbocharged. A turbo didn't come with the SE-R because of emissions and regulations at the time, but bolt on a turbo kit, and presto! Instant V8 Blender! Because of the made-for-a-turbo design, the SR20 can hold 20 pounds of boost (If you don't know, that's a lot of boost) on stock internals (Although your regular gas is nowhere near as boost resistant). With some other mods to aid the engine (intake, exhaust, fuel delivery, ECU, etc) and race gas, a turbo SE-R can easily push 300HP.  The same goes to the G20, later (not latest) SE-R, and 200SX, for they all come with the same SR20 engine and 5 speed tranny, although they do not handle as well as the classic SE-R (not saying that the handle bad).
              The KA24DE engine in the 240SX can be swapped out for an SR20, because that is the engine that it had in Japan (with the turbo and all). There are several places you can buy a SR20DET engine with a Japanese Silvia tranny, including Ebay, but installation of the engine will require more effort than a bolt on turbo kit. (The SR20DET will also fit in the SE-R, but the 240SX/Silvia tranny won't fit.) Now, the 240SX with or without a turbo will make a great drifting car (if you're into that thing). If not, it will also make a good track or autocross car; just try not to kick the tail out. 
             Some companies that make parts for the SE-R/G20/Sentra and 240SX are Turbonetics/FMAX, Greddy, JWT, and Stillen. If you want parts for the cars, some of the ads above will link you to performance part sites. (Performance parts Nissan Infiniti SR20DET Turbocharger) (Ignore that)
Pictures
Some 240's A G20
A 240 sliding G20 from diff. angle
G20, diff angle
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