No Power!!??

Hey guys, I'm a new 2015 FiST owner. Love this thing. It's a power house! Soo much fun to take on\off ramps with. I live in Wisconsin Where the winters are COLD (0-20 degree). So I switched from the stock summer tires, to the Bridgestone Blizzacks ws-80's tire for winter purposes only.

So, ever since I switched tires I have not experienced much power at all. The vehicle feels naturally aspirated at times, and at other times I get that same 'sensation' of speed. I can't figure out what is happeneing. But the vehicle has 4,000 miles on it, and for the first 3,500 miles it was an absolute blast! There is a clear difference between torque (or lack there of).

These are the things I have checked for already:

-intercooler hose clamps. (I tightened all 11 or so clamps so they are tight)
-Tire pressre. (It's all on at tire spec)
-Dealership checked it out. (vehicle did not draw any codes)
-"no"... I'm not getting used to the power this things puts out. (There is a HUGE differernce before and after)
-Traction control. (I've tested on and off. I've also kept a close eye on the TC light and it does not come one. The road conditions have been very dry for the past 3 weeks with absolutely no snow or ice on the ground at all.)

The pulls, and overtakes are not even close to what they used to be, and have not even 50% of the felt power as it used to be. So please guys, I'm dying to find out what the heck is going on with my new car. The dealership employees are morons, they took my car for a day and gave it back stating that everything is fine and the turbo works perfectly fine. But I'm tellin ya..... IT DOES NOT PULL NEARLY WHAT IT USED TO. PLZ HELP ME....

Thanks!