We will NEVER see sub four second runs, ever. Besides the limiting factors already mentioned you start getting into physical limitations which bring upon inherent dangers that cant be overcome. I think mid fours is just fine. Remember, the faster you go the harder it is to go faster. One big benefit of the performance limitations imposed by the NHRA is the fact that the tracks not getting oiled every run. I recall the days of clean up after clean up which nobody likes to see. They still pitch out some parts and oil once in a while but its a LOT better than it use to be. As stated before close competition keeps it interesting. Plus it still shakes my bones to see those cars go by. Just look at how popular fuel car test sessions are. Plenty of people go to watch TF testing because they're awesome to see. Pro stock holds its popularity because of the close finishes. Lets face it, they run straight as a string most of the time and would be somewhat like super classes if they werent chasing et records. For me, hitting Pomona, Infineon, LVMS for a few nats and nostalgia drags at Infineon, Famoso, sacramento and some sportsman stuff at sac and famoso gives me what I need for my drag racing fix. When my 40 dodge is done i'll try my luck in the brackets and life will BE ALL GOOD.