I could write quite a bit on this subject. A 170 thermo won't make much difference to an ST; it also will not gain you any horsepower. Most of the people (vendors) who supply these things are selling to people who still are thinking of carburetors, and heated intake manifolds, where that product might have had some impact on intake air temps.
In a modern GDI engine, the thermostat has very little, if any, impact on IAT. There are good reasons an engine comes with a specific thermostat that most people don't realize: mechanical clearances (piston-wall-ring clearance especially), optimal fuel burn (higher is better), oil temperature, closed-loop control, etc. I wouldn't put one in a modern GDI engine- it's just another throwback to older technology that makes money for vendors.
So, for the OP, it will have no real impact- and you won't have to revisit your tune. Even if it took 30 seconds and the product was free, I wouldn't bother.