I just did a time trail event with the Spark Racing Team at the Korean F1 track and I've got some observations I think you guys might find useful.
a. The track is marvelous. Tons and tons of high speed corners, lots of tricky sequences, lots of runoff and beautiful facilities. I'm pretty much in love with the pits. It's nowhere near as much a horsepower track as I feared it would be. In my 140~ hp, 2500~ lb car, the peak speed was only 147 km/hr.
b. As predicted, the 2.0 motorswap has transformed my Nubira from by far the slowest car on the straights to still the slowest car on the straights but kind of sort of competitive. I think this might have something to do with the god-awful cylinder head exhaust ports dumping into the god-awful manifold that dumps into an exhaust pipe necking down from the stock (god-awful) 2.0L oem downpipe to the stock (and even more god-awful) 1.5L oem catalyst/muffler/tip. Nothing says racecar like a 1.5 inch pea-shooter.
I'm going to buy a cylinder head out of the junkyard this winter and port the living crap out of it. If nothing else, the completely functionless, blocked off from the factory nozzle things in the head that obstruct at least 25% of the port volume are getting cut off and welded shut. The car might even rev past 5800 rpm this way.
I think that will go nicely with the race header the Spark Racing shop is making me and the custom intake I'm making. 160-170 hp might not be out of the question. If I get that much, I'm only 20 hp down on the big boys in my preferred TT200 class. I don't think this will be a problem, for reasons I'll explain a little later.
c. This engine puked a quart of oil out of the breather during a 30 minute session - almost the exact same thing the 1.5L did. Nobody but me seemed very concerned about this. Do I just need to install a catch-can/accumulator and forget about it? I'm probably getting an accusump when I come back to the states this winter, so I think that should cover my oiling needs.
d. I think my cooling mods are working. The car actually barely got up to temperature even while I was beating the living crap out of it for half an hour straight. Granted it was cold (45 degrees) outside, but still. I actually might need to block off some of the oil cooler for the winter because the car doesn't achieve normal temperatures, like ever, when I'm just putzing in cold weather.
e. I may need a brake upgrade. The slotted stockers were getting pretty smelly and turned blue. I have to check, but it looks like the 278 mm (vs 256 mm) rotors and associated calipers off a Chevrolet/Daewoo/Holden Epica will bolt on to my stock uprights. I might just grab the entire upright and, in doing so, replace the stupid wheel bolts with studs that render mounting the wheels much less of a pain in the ass.
f. I think I'm on to something with my suspension setup. My car is very sensitive to weight distribution and ride height changes, but with a .75 inch drop in front, a 1 inch drop in the rear, 9kg springs all around and no sway bars, this is one ridiculously sweet handing econobox. Basically suspension tuning in which I control roll stiffness by adjusting the roll centers. By keeping the car relatively high (and by lucking into some unusually factory geometry) I've been able to maintain good camber curves, high roll centers and close roll couples. While the car does roll a little bit (2.7 degrees total roll), it's not nearly as much as you'd expect and the transitions are very, very crisp.
The car is so adjustable, so neutral, so easy to toss around and it has just stupid cornering speeds. This is three track events now on this basic setup and in all three I basically corner as fast as comparable cars on whatever the next level of tire is. I have summer tires and my cornering speeds are about the same as guys on r-compounds (I actually reeled a few of them in during the twisty parts of the track). When I had crappy all seasons, my cornering speeds were right around what competitors with summer tires had. Nobody on street tires was even close. Not the BMWs, not the Genesis Coupes, not the Tiburons or Tuscanis, nothing.
More things I love about this setup include the ridiculously lite overall tire wear, the way I can run very little camber (about -1.5) without beating up the outside edges of the front tires and the fact that, in spite of being a FWD sedan with a 63% front weight bias, it wears the rear tires almost as much as the fronts.
I will never go back to slamming cars and putting on big swaybars. This works just so, so much better. I might need to bump up to 12 kg springs when I make the jump to r-comps, but the current setup is just wonderful. I really, really recommend trying it yourself.