My trans was hitting 219 and the bypass valve, TBV, was the first thing I removed. Then I figured out the coolant was still heating the trans to high temps so I got rid of that exchanger and put on the fan/cooler, under the truck, with a fan stat. Fan comes on at ~153 and shuts off ~140. Then the fluid goes thru the front air cooler. When I'm on the hiway, towing or not, the front cooler keep the trans temp down so the fan on the Derale doesn't even come on. My trans still gets to ~140 w/o the TBV. I got lucky, the Derale fan/cooler and the front air cooler work GREAT together. Craig