Welcome. There is plethora of knowledge here. Couple of things to consider. Removing the middle "muffler" could cause drone. The middle muffler is a resonator that helps keep the drone down. Also it has been proven that is doesn't provide hardly any performance enhancement.
For the tunes you are talking about, a stock exhaust will be more then adequate. Maybe a pair downpipes for a pitch change. To be honest the best exhaust mod that I have seen, is adding Anthony Di Cunzolo's upgraded TQ mounts. They are not for everyone, but they changed my exhaust in cabin sound more than anything else.
Tunes. LMS has fallen from grace in our community. Very few people will endorse them. You can read all about it here.
https://www.ecoboostperformanceforum.com/index.php/board,111.0.htmlI would look into other tuners personally. It seems for what you want, Gearhead's Auto Octane Tune is what you need. Matt (the Owner Of Gearhead) has brought this tune to market. The tune allows you put 87-93 octane in your vehicle without having to switch tunes. Also, the transmission tuning is top notch.
Differences in D to S will only be opitimized. If you are looking for a good all season tire, the Continental Extreme Contact DWS06 is a great tire. I have seen reviews from SHO owners saying they are good in the snow as well.
https://www.discounttire.com/buy-tires/continental-extreme-contact-dws-06/p/32246