Just looking for some insight.
 

I have an 06 base model with 134k miles on it and some pretty basic bolt-ons. I feel like the car starts acting sluggish around 3k to 5k rpms. The exhaust note changes under WOT. It's kind of a weird sound like it gets a little deeper. Once it gets past 5k rpm it pulls harder and the sound goes back to "normal". Can anyone say if they think maybe I need a tune to correct the issue or does it sound like a maintenance issue. My parts list is k&n intake motordyne mrev2 and plenum spacer, art pipes, shockwave exhaust if that helps pin point anything. Thanks in advance for any advice.

You are correct. Your ecu will never catch up to the changes without a reflash (tune). Good luck!

+1 on the tune. With your mods, my guess is your eco is running your car pretty lean. However, do keep in mind that our cars do have a sound change around 3k rpm so dont expect that to disappear. But the sluggishness is probably due to a lack of tune.

Thanks for the info!