If I remember right, 7psi of boost. Good pump gas boost (back when we had good pump gas).
So less then 160 ~ 170hp and it went out. Joe Weber had his SX 600 Vmax twin in for testing about the same time. Cranked the boost through the roof and made over 200hp without any issues. Thats why they stuck with the twin kits.
Look for odd plug reading if the crank goes out. Two will look good, one rich, low power..
Long time ago, my memory isn't what it use to be