I think none of these sets of headers are the same. especially if they were made over the span of 10 years or so. They may be the same part number, but they are not all built the same exact way.
I have hooker super comps that i can get in and out without doing anything and there is plenty oil filter clearance. But then you hear guys with the same set of hookers have problems. they have to be made differently in some way.