The Toyota Supra is one of the most upgradable sports cars in the market, unfortunately no longer in production in the US (I do believe it's still available in Japan, at least up until 1999). The latest and greatest top-end MKIV models featured a 320 horsepower (and 320 ft-lb torque) twin-turbocharged (intercooled) inline six-cylinder engine with a displacement of three liters. The engine is dual overhead cam (DOHC), but thanks to its inline nature, it only has two camshafts, which is one of the many benefits of an inline six. The basic (non-turbo) engine powers just about any Lexus with the number "300" in the designation, e.g. SC300, RX300, IS300, GS300... The engine has a cast iron block, allowing it to function under enormous boost pressures. In stock form, the rather heavy (3500 lbs) Supra rockets from 0 to 60 miles per hour in 5.0 to 5.3 seconds (depending on whose measurements you trust). This puts it roughly in the same performance category as the Corvette, Camaro, Ferrari 360 Modena, BMW Z8, etc. Though it's heavy, it's also aerodynamically impressive, with a drag coefficient of 0.33. On the skidpad, it can easily pull 0.95 to 0.98 lateral "gs" of acceleration.
But the best thing about the Supra is its capacity for upgrades. The most inexpensive "Basic Performance Upgrade" package recommended for the Supra totals to just over $2,000. This upgrade includes the following:
After these rather modest upgrades, a Supra owner can expect to produce 380 to 410 horsepower at the wheels. The 320 horsepower "stock" measurement is taken without considering driveline losses, meaning that in stock form it actually puts about 270 hp to the wheels. So for $2000, you can expect to add another 100 horsepower, which is quite a bargain considering the expensive and fruitless upgrades some people are known to dump onto low-performance cars to gain mediocre improvements in performance.
Of course, this is only the beginning. Powerhouse Racing, based out of Tyler, Texas, has produced the first street legal 10, 9, and 8-second Supras. They offer an enormous array of performance upgrades, allowing any serious enthusiast to go from 320 to 400 to 650 to 1000 horsepower...all you need is some serious cash. In order for the engine to safely handle 600+ horsepower, Powerhouse completely rebuilds the engine, performing the following:
If you're looking for 800+ horsepower and beyond, you'll need to do a lot more than that. For details, see www.mkiv.com, and www.powerhouseracing.com. Powerhouse Racing currently has the fastest unibody Supra on the planet, producing 1200 rear wheel horsepower. On May 16, 2001, they crossed into 8 second territory, pulling a 8.98 1/4 mile ET at 154 miles per hour. 0-154 in 9 seconds...damn.
Of course, it's almost impossible to find a decent MKIV Twin-Turbo Supra anymore. If you do, expect to pay at least $20,000, probably more like $25,000 to $30,000.