Some might call me crazy but I've had a spoiler come undone from my old Cuda body and it definitely made the car loose on entry off-throttle at high speed. I believe that's because my setup may have already been borderline loose at the time. If your setup has plenty of rear traction to begin with you probably would see no affect. I feel confident in saying my setup at the time was not all that great, nor were my driving skills. However, to answer the question... Yes, it did make a difference.