All these dynos were taken from another scion forum. I will gladly supply the link that has all this information at the bottom of this post.
Stock wHP is 136.84 as per
this dyno.
wHP with a Greddy Evo2 axleback is 142.16 according to
this dyno.
5.32 wHP gain.
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this dyno was done with the Greddy Evo2 axleback, but the gain is still the same.
wHP with stock headers is 141.17 and with Alphawerks header is 150.25 according to
this dyno.
gain of 9.08 wHP
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The intake dyno was done with Alphawerks headers on but like I mentioned above, the gain is the same.
wHP with stock air intake is 149.41 according to
this dyno
wHP with the Injen CAI was 157.50 according to
this dyno.
gain of 8.09 wHP
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From the tests used, there is a total of
22.49 wHP gained.
It may not be 35-45, but its still not that bad. Now if you add in some NST pulleys, and a Fidanza flywheel, you can probably pull close to another 10-20 HP out of your car. It's amazing what weight removal can do.
Also, as mentioned, the page I took this information from can be
found here. I had nothing to do with these tests, I was just using this to help me plan out some work for my car the other day and thought I'd help others out.