I just swapped out my 63/68/70 for a 66/74/80 because of too much drive pressure...I couldnt imagine what the back pressure would be with a 65mm exhaust wheel.
Just for reference, I have used a 66/71/80 before as well, and it was ok...I just wanted quicker spool up for the street.
Its not too bad, with a super b over a 475 I see about 95-100 psi drive at 85-90 psi boost. With my electronics off I see 55 psi drive with 62-65 psi boost.
*meant to quote extended's post
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