I don't know if the people who has one on their car really put the car on the dyno before and after but I did and the result was not good at all.
I put my car on the dyno ( Mustang Dyno ) so my car makes , 227.9 rwhp and 322.3 ft-lbs torque.
I put the dense charger reset battery etc. I get on the dyno , 225.3 rwhp and 321.3 not a big lost but the A/Fuel curve gets all screwed up cause of the Elbows .
Over that if you guys look at it carefully where the kit bolts to the MAFlow adaptor there is a big lip like the Dense charger adaptor is ( guessing ) 4 1/2" inside diameters and where it bolts it's like 4" so you get this big lip blocking the air flow and doing more turbulence , so elbows + this = very bad A/Fuel reading so this was where my lost came from .
Look here , I even had to port the Densecharger adaptor to make it smoother.
So what I learned from this is : The filter has to be as close as possible of the Mass air sensor and in straight lines ( like the factory ) to get the max from it.
I kept the tubing from the Throttle body to the MAF and bolted the filter right there. That way I got my numbers back and the fuel curve became nice and smooth.
I don't want to start a pissing contest but this is what I got from this modification.
I was like you , reading ( searching ) on Stangnet what people were saying about it and I thought : What about buying one and get it dynoed just to see what will be my gain. I was very dissapointed.
It does make me laugh when I read that someone put one on his car and he can feel the difference , common guys , even if the guy got 3 rwhp from a mod , how the heck can he feel the difference on a 3600 LBS car..
Maybe someone will have a different opinion with some dyno sheets to show us what it did to his ( her ) car.
I have more stories like that ( pulleys , chip , etc. ) always ( most of the time ) you have to cut in half what you read in the magazine ( horspowerwise )..