Could someone tell me how much mods I can get away with on my 2010 Kona Blue V6 Convertible. I want to install a CAI, 8.5cmm plug wires and E3 plugs. I want to do this WITHOUT needing to retune it.

 

I would go to the all the vendors sites and pick out the parts that interest you/fit your specific vehicle and talk to someone that works there, specifically a technically advanced person.
With the spark wires and plugs, you won't need a tune. Depending on the CAI, you may/may not need a tune.
Good luck!