I'm not trying to make any major mods. I'm thinking maybe just a K&N CAI and maybe another exhaust system. Do I need a tuner to make these changes? Will I still see improvement in MPG/HP without a tuner?

 

No I guess you don't "need" a tuner but if your already wanting to do a CAI and possibly exhaust a tuner is the basis for almost any other mod you do. Not to mention you can access your computer for codes ect.
You will probably see a small increase in MPG with the CAI.

 

You'll get more mpg with a CAI?

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2007 Vista Blue 4.0 Premium Package
8" shorty antenna

 

from what i've read, a CAI that doesn't require a tune, like the K&N, doesn't do much. it allows the same amount of air in so doesn't change anything.

you won't need a tune for the exhaust since it's expelling air. if you decide to get a tune, tell them you changed exhaust because they can custom tune that.