In an effort to reduce operating temperature on my 2009 ZX14 I am considering an Akrapovic 4 into 1 exhaust. Has anyone noticed lower coolant temperatures with the Akrapovic (or similar Yosh, Muzzy, etc.)? If yes, how many bars lower on the water temperature gauge?

Thanks in advance.

I have a Tsukigi. It is prolly a bit more open than most other ehaust. Really has no packing at all. My temps went down about 1 bar. Usually runs at 3, right in the middle. Hot day I will see 4. I still see 5 bars if it is a really hot day and I'm caught in traffic. I never see 6 bars. Think I did a few times with stock exhaust when the bike was new. Cold days, the bike is not likely to run above 2 bars on the highway.

As Rook stated, on my '06 and '08,,, Installing a Brock's Street Smart 4-1 and adding Water Wetter lowered my riding temps from 4-5 bars to 3-4 bars.
Power gains were awesome too!

If you're going to spend that much scratch attempting to lower ur temp gauge, try adding a second fan first...only about $50 bucks and you will see immediate changes in temp... buy the exhaust for more HP...

I was not aware an aftermarket exhaust could lower operating temps. Is this because the lack of catalysts mean less residual heat in the pipe? Or?

^^^That is what I always had assumed. No cats and all around better flow. Also less stuff there to hold onto heat. In street riding, my pipe usually does not get so hot you can't hold a hand on it. It is just barely warm after the bike is shut down for 10 minutes.

just added a muzzy full system, pcv+autotune and a second fan to mine and the heat is definitely more manageable and the second fan seems to cool it down quicker. I also think i am not getting the scorching heat i was on my right leg like i was stock when outside temps are 90+. The weight loss and power gain are worth it alone, but less heat makes it even sweeter.