Mixdown exports a -3db peak file, after limiting to a metered -0db brick wall.

We know nothing about your external plugins, and what effects they may be having on your mix. But please note the last thing I said in the link - and that's the bit that unfortunately SuiteSpot hasn't clarified - if you just change the pan setting, then even with a restart it won't necessarily alter anything about a session you've previously created. I'm sure that it's possible, but you need the details of what to alter in the .sesx file to achieve this.

The other thing of course is that with 32-bit Floating Point mixes, it really doesn't matter what the final level is, as long as it sounds okay when you play it. All you have to do is open the exported file in Waveform view and normalize it to 0dB, and you will have hit the peak value far more accurately than any effect in the master channel will.