I will answer Art's questions first; the 3rd line coming out the back of the regulator is for the fuel pressure gauge mounted on the cowl. I have a Mallory 240 GPH gerotor fuel pump; it is hooked up with a return, but has it's own internal regulator that sends the excess fuel directly back to the tank. In the future I may run a 2nd line and switch to a front mounted 4-port regulator. That would keep the fuel much cooler; on hot, sunny days with long waits in the staging lanes I sometimes experience fluctuations in pressure that I have traced to the regulator experiencing "heat soak". The spring inside the regulator actually expands and lowers the pressure. Weird problem, now partially solved by moving the regulator away from the hot air coming from the electric fan.
The use of computer(actually just a timer) controlled throttle stops does indeed make for a strange sight, especially in a class like Q/R where almost everyone has one. At most tracks, Quick Rod runs an 8.90 index and some of these dragsters have upwards of 2000HP and are capable of mid 6-sec runs at over 200 MPH. Slowed to the index, they still post big MPH numbers as high as 180, in a class that a unrestricted car would barely break 150. If you watch carefully, not all of them are configured the same way; some close the throttle a whole bunch immediately after launch and then snap open a few seconds later, usually after the trans has shifted into high gear. Others do engage a little later and come back on slowly. A friend of mine used to race a 1000HP BBC powered Datsun 240Z in Hot Rod with a 10.90 index; the car, capable of mid 8's without the throttle stop, spent 4 or 5 seconds right after launch just idling down the track and then yank the front wheels after it was out about 500ft. I actually heard an unknowing spectator tell him "once you get the bog out of that car I know it will be really quick". We just about wet ourselves laughing!