So, I'm sure you guys have seen devices like this before. I have something similar that is made for my truck that only cost me $30. What the device is doing is changing the resistance in the Air Temperature sensor. The one I have is a fixed resistor so that in the hot months you put it on and it provides winter like performance. I'd be highly surprised if you could get 15% better with it. But during the summer it would be a good add on if cheaper.
https://www.ebay.com/itm/DYNO-BOOST-...4383.l4275.c10