Unless they are the anti-reversion (?) style headers. Ken Quoting Tom Jennings <tomj@xxxxxxx>: > Hey, it just occurred to me, for testing headers for flow, which > sounds like a bunch of effort since there's 4 outlets (per V8 > side), why not flow them backwards? > > Attach the outlet (bottom) to an air source, put a false extention > on the "inlet" end for a few inches, measure pressure/flow there? > Pipe is stupid, it doesn't know left from right. > > > > > >