Your sig does not list any power enhancements so I would tell you to leave it alone. The stock transmission behind a stock engine is a tough unit. It gets beat up on here quite a bit, but it would shock you to know how tough it really is. Even towing really heavy loads I would leave it alone with stock power, just keep the RPM up and let it lock when ever you can get it to lock. Let out of the power a tad when it is shifting and when it is locking up, then get right back in it. The other thing that will help it live is don't baby it around! Get up to speed and go, and don't downshift it manually. Especially towing don't baby it, use it hard but don't abuse it is what I am getting at. These transmissions like high RPM and heavier throttle positions.
You can go to DTT's website and they have directions for turning the line pressure up, it will tell you how to check the pressures as well. If you are on the low side for pressures turn it up to the high end of spec. If you are in spec leave it alone. The line pressure is really the only thing you can do short of mods to help it live. Hope this helps.