Porsche's über 911, the 2008 GT2, has been spotted by spy photographers undergoing testing ahead of its launch at September's Frankfurt Auto Show, and this time on U.S. soil. The near-complete test mule was totally undisguised and has revealed important clues as to what the final car will look like.

A key difference of the GT2 over the lesser Turbo is the enlarged front air-intake, new lower lip and cooling vents positioned in the rear bumper. The oversized rear wing is probably only there for testing purposes and will likely be toned down for the production version.

Powering the coupe is a worked version of the 911 Turbo's twin-turbo 3.6-liter flat-six, sending around 520hp to the rear wheels. Expect a top speed in excess of 200mph and acceleration times for the 0 to 60mph sprint in less than 3.7 seconds.

To improve performance further, engineers have removed the air-conditioner and sound deadening to save weight, and Motor Trend reports that buyers will be able to opt for a roll-cage, one-piece racing seats and a fire extinguisher at no extra charge. You'd expect some extras thrown in considering that buyers will have to fork up close to $150,000 for the performance coupe.

[Source: Motor Trend]