Granted, he did pay for the potential to have that last 20 HP with at least some of the first $6k!Agreed PJ. One of the racing forum members here dynoed his car, made 160 hp at the rear wheels. The dyno operator rejetted the carbs and played with his ignition timing, he got up to 181 hp at the rear wheels in 30 minutes. Even if it cost him $300, that's the cheapest 20 HP he's ever paid for! I guarantee the first 160 hp cost him $6000 or so.
I think most anyone can tune 80% of their engine performance just with their nose and seat of the pants feelings. But to make any real amount of power or true maximum economy - as in any true 'performance' of the engine - a dyno with an operator who knows how to use it is the only way to truly maximize all of the gains.