We took the TR off our 655 and threw it on the 572 then threw the 572 in the car. The ports are mismatched (572 -13 v's 600 -13's), the hood isn't sealed, the carbs are too big (2 x 1150) but we've been within 1 MPH of the best the 572 has been with a single 4. We can't get it off the line yet (too many chassis changes) and the fueling isn't there either (lack of runs) When it all comes together I'm sure it will out run the single 4, which was a 440-3X with a well sorted out 1200 cfm pro systems dominator.