I have a real world comparison between extrude honed stock manifolds and a set of TTI headers on my old 70 340 swinger.
The engine was the original 340 that was bored .030 over with a somewhat hot hyd cam from Hughes engines and an Edelbrock RPM intake and Holley 3310 carb, heads had Hughes stage 1 porting done to them. Had the original 727 trans with shift kit and 2800rpm stall converter and 355 gears. I had the stock manifolds connected to the TTI system from the headpipes back and the car ran a best of 13.46@101mph. I then installed a set of TTI stepped headers and with no other changes ran a 12.76@106 on its first run down the track. So is the extrude hone worth it, not in my opinion.