You could make more power out of that displacement if you designed the engine to rev higher. The tC engine is straight outta the Camry, Solara, RAV4 and Highlander. It's not a revver. The kit is also sold as a dealer-installed accessory for brand new cars, and as such is covered under the factory warranty. They need to be conservative enough with it that it'll be reasonably reliable even though dealers are installing it.

And gee thanks rick, that picture wasn't quite big enough!