it is important to butter fly cut the back strap..or you will have a tough outer with a raw inner....if the back strap is huge, double butter fly cut it..but normally just once is enough...if you have your smoker at 250-300, it will be plenty enough time..10-15 minutes per side..15 if you are at 250, and 10 if you are at 300..the loins will be 5-10 minutes...

you heard the guy say below..he had it once, it was tough and dry(or whatever)..this is product of over cooking.