06 LS doesnt feel as powerful as should be?

I got an 06 LS cobalt sedan, my girlfriend has an 05 sedan as well we both have the same 2.2 ecotec motor, all stock. her 05 seems a bit more powerful and responsive on acceleration than mine. i got no check engine light or starting issues and i jus replaced the air filter. if i stomp on the gas it gets up and goes jus fine. my car only has 31k miles too. anything i should investigate or is it jus my imagination??

this section sucks!