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I would suggest cooking until an internal of about 150, remove from the heat, cover in foil and allow to rest for about 20 minutes. You might want to go as high as 155 before pulling.
You will come out with such a moist, tender and flavorful loin, also as it rests the temperature will continue to rise a few degrees.
According to the USDA and the pork council, 137 degrees is the temp that pathogens are killed off. I personally pull my tenderloins when the hit 140 and I wrap in foil and let set up for 15-20 minutes. This allows the pork internal temp to reach 145-150 and retain moisture.
Some people prefer to wait until their's has hit 150-160.
Pull it not later than 155 and foil to rest. It will be good and done and still tender. Anything much above this and you'll be drying it out and loins and tenderloins are really easy to dry out.