Road & Track
I would buy the 600 hp car but not because of the warranty. The December issue of Road & Track magazine has a pretty extensive road test of the 600 hp car. The super snake is only 2/10 of a second faster zero to 60 than the stock car, and only 3/10 of a second faster in the quarter-mile. With so much of the cars weight directly over the front axle, the Super Snake may have 600 hp but it only has about 400 hp worth of traction. "Massive wheelspin in the first two gears" was the reason the big increase in horsepower did not result in a significant increase in acceleration. I have the same problem with my Kirkham. It has 650 hp, but only about 300 hp worth of traction. If I was able to pump my Cobra up to 1000 hp, it wouldn't be any faster at all until I reached higher speeds where traction was no longer an issue. Even with the best tires, the magazine test clearly indicates that 600 hp overwhelms the available traction in the GT500. The 600 hp car will probably be more drivable, more reliable, every bit as fast zero to 60, AND, just in case you need it, a warranty. Up to 60 mph the 700 hp car will provide only additional tire smoke. That's my opinion and it's worth every dime you just paid for it.
Chip