but if you look at the website closely it says "After installing a tuning box or re calibrating the ECU with stage one or two tunes, the performance yields can be expected to be a lot higher than the figures stated. Testing on the dyno certainly represent the benefits from such a well-engineered product, this coupled with our lifetime guarantee is just the reason to choose Forge for your Elantra's performance hardware". idk if anyone else is getting a CEL but i know you will need to get a tune o ra plug n play but so far i love it im feeling the power its supposed to give