
Might wanna check a different builders numbers.. not the youtube blow it up for clicks guy.... Terry builds tons of strokers and dynos them all (i shoulda bought a shortblock from him.. woulda been done already)

Those are big numbers! It's in the heads!![]()
When Imca changed the rules from manifolds to shorty headers with 2" pipes the gain was usually 25 average hp between 4500 to 7000 rpm. These were ported lt1 manifolds (good manifolds) on spec 360 cubic inch limit motors with 2bbl rodchester carburetors. I expect this 390 would bump the numbers a bit with headers.Those numbers don’t look bad to me for ex manifolds.
You noticed the blow by too. At work we had a truck with blow by like that, it was enough to push the dipstick out sometimes.That has been posted numerous times in the past. It's also a poor build, has massive blow by, and weak numbers for a 4" stroke build. It's a turd