I'm still using stock headers and they make good power with a fairly quick spool of my 62 turbo. I run a 3" downpipe that splits into two 2-1/2 exhaust pipes over the axle to the stock location behind the rear wheels. Nothing radical here. I welded them up with bracing a few years back, had them squared and they haven given me any problems since. I'm happy with he setup but had to make a new crossover pipe due to it splitting.
I've run a best of 11.18 @ 123 mph on a 109 block with cleaned up iron heads and cleaned up port matched stock intake setup. That 123 mph means I could go high 10's if I try. My only issue really is the 50# injectors that run out of fuel even with two #15 nozzles on the progressive alky setup (need to do some tuning now).
I road tested a stock appearing GN in Jacksonville some yahoo put 2" headers on with a big turbo and the thing was a dog for what he claimed he had in it. Would not build over 14# boost (took forever to get to the 14# too) and no faster than a bone stock turbo. My son was with me in the back seat and asked the owner, who thought it ran great, why the car was soooooooo slow. I took him for a ride in mine and he wanted to know how to get his to do the same. I told him to start over.
Mikey