Water Temp sender

[Faster & Mor Furious]

Anyone ever tried to install an aftermarket water temp guage on a 99+ stang? I tried to put one on mine and had few problems. By installing a T-fitting and running the new sender and the factory sender, i would only get a reading above 1500rpm and i don't think it was accurate (never hit optimum range). I tried disconnecting the factory sender all together and replacing it with the autometer one only to find out that my electric fan no longer worked and the car ran hot. Thinking that because it is a pressurized system i tried tapping the autometer sender in the bottom of the overflow resevoir, that setup stays around 115-120 degrees. Anyone have any suggestions here? I would just swap it for a trans temp but i can't find anywhere to put that sensor either.