Kenny's spot on. If REALLY tight (shouldn't be, lots of room in Impala engine bay), try removing 1 motor-mount bolt at a time, and jack that side for clearance.
Double check that you have the correct header for your specific chassis, as THAT will certainly create small to large issues with fitment.
camshaftshaun@gmail.com
usually the issue is clearance, so most of the time one slides the header from bottom up.
The "Easiest" way to do it is take the car to a shop where they are familiar with this project, and PAY THEM to do it.
Got some long tube headers for my car, would like to know the best way, or easiest way to install them, thanks.
