Bullhorns are absolutely neccesary for downforce, but they are also the worst offenders of drag on your race car.
Innovators in bullhorn style exhaust, LP Racing has always been at the pinnacle of using exhaust forces to their benefit.
Because of current chassis technology, maximum downforce is required at all times. The effects of a round tube sticking out 10-15" out of your door completely negates all aerodynamic efforts made.
Available in 3D printed Inconel, for nitrous and blown applications - Call for Pricing