The owner of this engine is a wrench and part owner of a very successful NMCA Mustang and has many race cars under his belt. I built the shortblock and degreed the cam. He added the top end and dyno'd the engine. I wasn't aware he was testing anything and while I'd question many others' results just as you did - I have learned after talking to him there's no reason to question this guy. The numbers may be a little off accounting for typical dyno shenanigans, but the change was significant and very apparent. These were both tuned on the pump although i don't think they tried to wring every last ounce from the Air Gap combo because he was going with the six pac regardless. Tune all you want - the intake is restrictive on a 4" stroke engine. It's reality - not pessemism.
