It all comes down to this. How well does your car perform? The dynamometer is the one true test. 0-60, 1/4 mile, and other acceleration measurements all depend on the most uncontrollable variable of all - the driver. A dyno is a machine, precisely calibrated and design to eliminate the uncertainty created due to human faults.
My car was dyno'd at Frey Racing in Mountain View, CA, in January of 1999. I knew not to expect much, only a homebuilt intake separated my powertrain from a stock one. The car had about 40k miles on a rebuilt engine, running premium fuel of course (92 octane - but note, this is California gas, with that damn MTBE, proven to reduce power slightly).
The result? Well, first of all, my homebuilt air intake actually ended up REDUCING horsepower by about 1.5hp. This is most likely due to the sharp 90 degree bends I used (not many options when working with PVC pipe <grin>), and the warmer air being injected (the filter does not extend very far down towards the side air scoop). A longer intake tube and gentler radii on the bends would help.
Of course, the whole point of this dyno testing was to test the performance of the ERam on a naturally aspirated MR2. Mark Kibort was kind enough to pay for the dyno time, how could I refuse? The ERam is, essentially, a low boost electric supercharger. While it doesn't develop much boost, it has been shown to produce 3-5% increases on most cars. On my car, the results were at the bottom end of that range, somewhat disappointing but it DID work as claimed. The photo shows the Eram installed to a jury-rigged intake. We also tested it attached to the stock airbox, and found that power was slightly better in that configuration. It made no noticeable difference whether an air filter was attached to the ERam.
Ok, enough blabbing, here's the results of my car's first dyno session, click the image to get a larger view. This graph compares the ERam to my custom intake, the stock intake produced about 1.5hp more so I'm at about 105-106hp (at the wheels).