our local drag races doesn't ask for a blow down tube. and when i went to the track where i ran 11.5 i didn't put the NOS bottle in when i went through tech told them i would probably try 1 run on juice but thats it. they didn't even ask bout blow down tube. now i have 1. i want to go to a 1/4 track at sea lvl and they are a nhra event track so they a heavier on the tech so they don't lose there event.