rdfrederick87 asked a perfectly reasonable question, in my opinion. Heck, you can even purchase upgraded engine components for a VW Beetle. Cut him some slack!What makes you think that engine internals for an economy class car would exist at all? Why in the heck would you even consider something like that when better performance cars exist that you can purchase? Seems to me like your suffering from I can mod anything to go faster disease. The cure is simple, learn more about cars, learn that if you want corvette level performance you need to buy a corvette lol. If you can't afford it, save your money instead of trying to make an econobox go faster. Ever heard of the Focus ST? The Mazda 3 Speed? Both are far better platforms for power mods than a base Mazda 3. Fiesta ST with a healthy cobb stage kit? So many better options out there man. If your willing to spend thousands of dollars trying to squeeze another 50hp from a base Mazda 3 then I highly recommend selling/trading your Mazda 3 for something better, factory boosted, and start there. Some may disagree with me, but the fact is simple, you want to go faster, and to do that without wasting money requires a better platform to work with. I highly recommend the Focus ST or Fiesta ST, maybe a Cobalt Turbo(2008-2010), Genesis Coupe? Mustang Ecoboost? Oh and stay away from JDM RHD imports, they require more money than its worth, ask my old Subaru how I learned that. They seem like a wicked deal, but their not, unless you have lots of money and don't require a reliable daily driver.