I have a spare intake manifold assembly that was extrude honed. It feels very smooth to the touch internally, but I was wondering if having it P&P would make a difference? I know a shop I used to goto for work that will do the same type of polish as SHM (cut off the bottom, work the inside, and weld it back up [see photo below]) for a fraction of what SHM wants (900.00 for labor @ SHM). SHM claims a 20% increase in air flow, which I assume is from a stock intake. Does the extrude honed intake already have that air flow capability? I see from previous posts that extrude honed intakes are much more desirable than acid dips. Anybody have any figures on stock vs. acid vs. extrude vs. P&P intakes? Just wondering if I should work the intake or leave it as is and save it for a future project. 
