The cars were "popping" like mad even under acceleration.
I could see the flames from the front and it looked like they were
coming from the wastegate.
What causes this?
Is it the wastegate?
Is the car running properly?
Thanks
Mike

 

Anti-lag system? http://www.rallycars.com/Cars/bangbang.html

 

It's called backfire, where the fuel of the car is not burnt prop in the engine, thus the excess fuel comes out of the exhaust system, but since it's hot, the fuel than gets burnt there and therefore produces a 'bang' sound as well as a flash of light that looks like a spark.