Noticeably reduced performance with A/C on. Also squeaky center console/vents.
 

I have the 3.0.
During the summer while using the A/C, I could feel the engine's lower power ouput. Overtaking a moderately accelerating car, I had to use caution. But with the A/C off, I can feel more power and responsiveness.
I know the A/C steals some horsepowers but do you notice the difference like I do? Something to take to the dealer for?

Also with the A/C on, lots of squeaks come from the center vents and console. This is so very annoying! So much squeak and the noise is made again when I'm taking moderate, harder corners. Any solution for this?

I have not experienced these problems with my 3.0 model. I guess I can't absolutely swear that the A/c has not diminished my acceleration, but if it has, then the transmission and gearing are doing a good job of covering it up. I certainly don't experience the vent and console based noises you mention!

I have 3.0si as well, did not notice any performance difference with or without AC. Just noticed idle rpms are higher with AC on.

AC fans are another story, with rear AC on there is annoying high pitch noise from the console.

Thans for the replies!

I don't even think I can take it to the dealer, knowing they'll say it's normal.

Just not using the A/C is the best solution for now...