Disappointed in my 383 on the Dyno

Could have been Hedmen 78030 B-body headers in an A-body, they fit with manual steering and low deck engine.
I've used them in multiple A- bodies over the years and with very few dings.
They actually fit pretty well. imo
Maybe that's what it was .it looked like they fit around the starter better.My tti on my 470 is very close and I have a mini but they were on my 440.But it fits beautiful on the rt side .Changing plugs is a breeze. With the 440 it sucked.They have dings in them for the Manuel strg and stuff