I've been using the 5-3-1 program for 8 weeks now and have been using the trap bar for my dead lift days. I follow the BBB regimen and use the barbell occasionally for the 5x10s. I calculate my percentages off of a 345# max. I'd like to transition from the trap bar to the barbell and was wondering if I should decrease my max a certain percentage while making the transition. Thanks.
I transitioned last summer and I would guesstimate that dropping 10% would have been the best fit at the time, your mileage may vary.
Why don't use just start with 135. Then go up in 10% increments (35 pounds). Stop when you get to a fairly hard set of 5. Calculate.
There is no % - do it right.
There is no magical percentage. I've seen people pull more on the trap bar than the barbell, and I've seen people pull more on the barbell than the trap bar. Take a day, work up, and find a new max.