Because I'm as indecisive as the rest of you I thought I'd throw this up here. I'm leaning toward the bottle but who knows. Basically I'm budgeted for one or the other.
Converter then spray. Suspension before both.
IMO...unless you're going to be running the track A LOT, id go with spray first because its just fun, you can play with that anywhere. then suspension. then converter
Details on your set-up?
I've grown to like using the power I have. Blowing the tires off is fun for a few days.