727 shifting in drag race??

Thanks for all the help here. I am familiar with the 1st gear issues. We will avoid that at all costs. When shifting, do you let off the gas or just keep the pedal down? Kind of a dumb question but my manual transmission brain is confused.
pedal down.... manual, unless you are slamming gears would make the engine rpm spike when clutch/shifting, autos shift pretty instant so no need to mess around