How much faster or quicker would a stock 03 sixxer feel after it gets a CAI and tune?

 

CAI-very little to nothing (tuner might help but not a whole lot, its not like the S197s)

Tuner-really depends on what tune you run and what other mods you have. Various mods will see more gain with a tuner. But again it depends on the tune.

In reality, the 3.8 isn't overly mod friendly. Yes you can see decent gains but nothing crazy and it takes a lot to see those gains.

 

Yes sadly it isn't as "bolt-on" happy as our bigger v8 brethren. Takes a little more money and mods to get comparable HP gain. Some people claim like 10-15 with a CAI with a tune but idk how legit this is. Unless you do some modding to your manifold a CAI doesnt do much.