They’ve done a 710 HP version of the R8 V10, why not add more power to the V8 variant of the R8 as well?
The tuners from STaSIS are introducing the Audi R8 V8 Challenge Extreme Edition, a car which generates 120 bhp more than the standard model (a total of 540 bhp and 435 lf-ft of torque) and weights less than the factory V10.
The upgrade in performance was made possible by adding an Eaton / Magnusson TVS 1900 supercharger, an independent charge cooler system and a revised ECU. Audi R8 V8 Challenge Extreme Edition has also received a cross flow, stainless steel exhaust system which reduces back pressure and increases power, as well as bigger brakes (390mm front / 355mm rear from Alcon) featuring two piece floating discs.
The suspension has been lowered in order to improve handling plus the Audi R8 V8 Challenge Extreme Edition is now riding on 20 inch ultra lightweight forge aluminium wheels wrapped in high performance tires.
An now we arrive to the best part. The Audi R8 V8 Challenge Extreme Edition by STaSIS sprints from 0 to 60 mph in 3.6 seconds (0.8 seconds faster than the standard V8 and 0.1 seconds faster than the stock V10) and its lateral acceleration has increased from 0.96 G to 1.01 G. 

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Specifications : Audi R8 V8 Challenge Extreme Edition by STaSIS 

  Factory Audi
R8 V8  
STaSIS Audi R8    
V8 Challenge Extreme Edition 
Factory Audi
R8 V10
Power:  420 bhp   540 bhp   525 bhp
Torque:  350 lb.ft   435 lb.ft     391 lb.ft  
Weight: 1560 kilos   1575 kilos 1620 kilos
0-60 mph: 4.4 sec  3.6 sec   3.7 sec
Lateral accel’:  0.96 G  1.01 G   0.99 G
Brake decel’:  1.04 G   1.06 G    1.02 G
Source: STaSIS