John
nitrous filter yes,just before carb,purge and blow off valve NO,you are not going to run 250-400hp nos thru that motor and go thru 10-20 bottles a season,pros use the purge and show offs at the track with small systems,us regular guys just hit the button a few times during the burn out part of our run, save your money on the trinkets and invest in saftey items,my two cents,,,
Charles