how much pipe off stock manafold for break in?

[mosquito13]

i have a set of borrowed stock manifolds for breakin' in my engine installed in the car. ceramic headers for latter. how long of a length pipe should i have off the manifolds. just long enough to get the heat away from the car?

 

[RustyRatRod]

As long as there no wiring or anything flammable under the outlets, run them open. It won't hurt a thing.