Stock tensioner with a metco brace. Gen2 (non crusher) makes around 750 on e85.
Maybe something was wrong with my car but I bought it with a 3.4 crusher. It had a 3.2 RR no slip, and 6lb lower 5.0 mmr with slightly upped compression and long tubes. It slipped to 24ish when I bought it. I bought a manual tensioner and it didn't help. Bought 3 new belts in 2 weeks and couldn't get more than 16ish lbs out of it. One of those belts I even went shorter to the point the tensioner barely released from being maxed out lol. My lower pulley was a little loose, but I spun the key way on the crank, and cracked the crank all the way into the motor.
Wish you the best of luck! I went turbo and have had nothing but problems.