[18degsbcregal]

Lifter preload ok? Spark plug wires/coils/plugs in good shape? Any plugs look different than the rest? Sounds like there’s an issue for sure. I’d think it should make 550 or so on wastegate spring. With reasonable timing.

 

[18degsbcregal]

FWIW also, the TH400/9” combo will show a good bit less power on the chassis dyno than a C5 corvette drivetrain, or a T56. What kind of tires/wheels were on it? Also, that sniper intake is a dog at lower RPM. What RPM did you pull it to?

 

[18degsbcregal]

Blowing through the converter?