British car maker Aston Martin has released preliminary information as well as photos with the 2011 Vantage GT4.
Still based on the road going V8 Vantage and featuring a remapped 4.7-litre engine the manufacturer says the 2011 Aston Martin Vantage GT4 offers increased levels of power and torque, but unfortunately no exact figures have been mentioned.
Enhanced aerodynamics and increased levels of downforce were also achieved and for the first time, the automaker allows customers to choose a race-developed Bosch ABS and traction control system for their 2011 Aston Martin Vantage GT4.
The 2011 Aston Martin Vantage GT4 will be eligible to compete in the European GT4 Cup and all other series with a GT4 class, and as far as pricing, no details have been specified yet. 
Aston Martin press release :
Gaydon, 25 November 2010. Aston Martin Racing has launched a new
Vantage GT4 for 2011. The new V8 engined racing car takes design
inspiration from Aston Martin’s V12 Vantage road car, giving it enhanced
aerodynamics and increased downforce. It also has a remapped 4.7 litre
engine offering increased levels of power and torque.
As with the current 4.7 litre Vantage GT4, which made its race debut
in 2009, the 2011 car is closely based on the V8 Vantage road car with
key attributes being carried over including the aluminium chassis, base
engine and suspension design.  In addition to the engine and aero
upgrades, competitors can, for the first time, choose a race-developed
Bosch ABS and traction control system.  This system has been
specifically optimised by Bosch Motorsport for the Vantage GT4 to
provide   race-enhanced performance in both wet and dry conditions.
The Vantage GT4’s new splitter increases downforce at the front of
the car, as well as channelling cooling air to the brakes and radiator. 
At the rear, the car gains the V12’s larger boot ‘flip’.  This works
together with a new carbon fibre diffuser and rear underfloor, which
create an area of low pressure under the rear of the car, to increase
downforce.  The redesigned underfloor also channels more air through a
new rear-mounted high capacity transmission oil cooler.
Aston Martin Racing has built and sold more than 80 Vantage GT4s to
customers around the world in the last two years and it has become the
most successful car in its class.  In 2010, it won the European GT4 Cup
as well as the GT4 class at the Dubai 24 Hours, the Nürburgring 24 Hours
and the Spa 24 hours.  The car also has its own one-make series, the
Aston Martin GT4 Challenge of Great Britain, which was won in its
inaugural year by Chris and Ant Scragg.  The new Vantage GT4 will be
eligible for this Challenge, as well as the European GT4 Cup and all
other series with a GT4 class.

Source: Aston Martin