The reason for that, the drop in temperature of air after the usage of cold air intake system is small which hardly boosts up any performance. (motorbeam.com)
If you want your upgrade to be as efficient as possible you can also buy cold air intake and cat - back performance exhaust system. (mywikimotors.com)
The check engine light came on 3 months after installing the new cold air intake. (mechanics.stackexchange.com)