I'll just cut to the chase. Been having a back and forth on a different forum where someone was claiming significant horsepower gains by just reducing exhaust restriction on the current gen Toyota Corolla with the M20A engine. My stance was that any aftermarket exhaust system would only be for sound, aesthetics, and maybe weight savings.
So he produced a dyno chart posted on 2JRacing's FB page showing by adding an intake, headers, less restrictive mid pipe, and cat back that they were able to get 30WHP gain on the factory tune. To me this doesn't pass the smell test as that's huge for what amounts to be an econobox that is naturally aspirated. I also looked deeper into the dyno run where they claim the base line run put the horsepower at 151whp. That didn't seem right to me assuming a 20% loss would mean they're claiming the stock setup is at 189 crank HP. The factory rating is 168 HP. With their mods, their dyno run shows 180whp which would translate to 225 HP at the crank. So in essence, this tuner is claiming a 33% increase in just bolting on an intake and exhaust over the factory HP number or 20% over their measured stock baseline with no tune.
Something doesn't add up. What are your thoughts?
