Nitrous

Those are neat little kits.   About $20 or less to fill the bottle.  However the gains are almost nill.  I doubt you would even get a full 1/4 mile pass out of the bottle.  A 50hp nitrous shot in a 2.8 is barley even noticeable.  Your motor has to be set up right and the conditions of the shot have to be exact, in order to really see the power out of such a small shot and being a dry shot it makes even less difference than a wet shot.  Notice there are no solenoids, as it is all controlled with valves and such.   I don't know about you, but the last thing I would want to be playing with is valves on a bottle in the middle of a race.  Heck having a push button on my shifter to hit the nitrous was almost too much of a hassle, I firmly believe that a throttle actuated switch on a solenoid is the only way to go.  If you really want nitrous go the big way and get a 10lb bottle which will last 10 pass at the track or a full night of playing with the locals at the cruise In's.