Sorry, I need clarifications "NA" means stock? My car has Injen CAI and cat back, will it still worth the money.. I am still waiting email reply from Unichip for the number of hp gain in Injen CAI and cat back Also, whether the wiring point is the same.. and ask them to send me the installation menu I have troubles to find out how many hp people actually gain for different types of setup and vehicles, even for non Corolla cars NA means "Naturally Aspirated" in other words no forced induction for example no turbo or supercharger. I mate of mine installed a piggy back on his swift and it did nothing. I think these sort of systems are kinda like those battery power superchargers, gimmicky and very hit and miss. Unless you have money to burn, I would stick with tried and true methods, for $500 CES can send you good extractors with decent gains for the price.