Yeah I think I heard around $2000 and it takes the HP up to 300HP. I just really can't find info on it. Here is the one link I found.
http://autos.msn.com/advice/article.aspx?contentid=4024238
"Accessorizing
For those who aren't satisfied with a stock MAZDASPEED3, there are plenty of parts available from Mazda that can enhance style, handling or power.
"Our objective with the Mazda Accessories program is to provide products that actually enhance the driving experience for Mazda customers," said Jack Stavana, director of accessory operations for Mazda North America. "Mazda drivers are young and passionate, and Mazda accessories provide them with the means of expressing their enthusiasm on their vehicle."
To illustrate some of the customizing that can be done to a MAZDASPEED3, Stavana had a special MAZDASPEED3 at the track, outfitted with suspension upgrades, new wheels and a cold air intake. Stavana said the cold air intake adds about 30 horsepower, with virtually no increase in emissions. And, as with all other genuine Mazda accessories, the alterations are all covered by the factory warranty.
We drove this customized car on the track and were extremely impressed. With the additional power and firmer suspension, we were going into turns as much as 20 mph faster than with the unaltered MAZDASPEED3. The suspension would probably provide a rough ride on the street, but on track it felt superb.
Stavana said that prices had not been finalized yet for these parts, but he estimated that the changes made to his car were valued around $2,500. The cold air intake alone is under $1,000, which means you could have a MAZDASPEED3 with almost 300 horsepower for under $25,000! Which brings us to the best part. "
~Thanks
John G