Don't think so, and after seeing the British Grand Prix from the bottom of the seating area just before abbey hairpin, where we were pretty damn close to the cars as they passed on full throttle, then watched them downshifting to second gear and turn in to abbey, I whave to say that thought they are incredibly loud, (the force is actually physical), there were absolutely no exhaust flames at all.
Exhaust flames result from unburnt fuel being dumped out into the exhaust system and being ignited by the very high temperatures present. (Often seen from Turbo systems which are no longer used in F1).
This is inefficient as unburnt fuel is not generating any useful power driving the cars forward, and also increase fuel consumption. Modern F1 V10 engines attempt to optimize as much as possible fuel efficiency and power / torque etc and wasting fuel is undesirable, as it means you have to carry more fuel to travel the same number of laps, carry more weight and achieve slower lap times (slower cornering etc).
To add exhaust flames to GP4 would not exactly be "realistic" therefore.
If you really need exhaust flames try Drag Racing. (not a fuel efficient sport. it's all about POWER..!!)