Is this Factory? 307 exhaust headpipe restriction?

[andymarkv]

Hey guys!
I just replaced the driverside exhaust manifold outlet studs on a '71 C20 Longhorn with 307/4sp.




I found this reducer/gasket/adapter in the end of the head pipe? Its basically a donut gasket on a flanged piece of pipe that fits inside the end of the head pipe. The issue is the pipe starts at 2" diameter and necks down to 1 1/8"!!!
Has other people seen this? Is it also in the passenger side?



Before I put it back together I used a cut-off wheel to trim it to 1 3/4" diameter, from the tiny 1 1/8".

Now here is the surprising part, it really runs better. I mean its VERY noticeable. Back in 2010 I put in a small comp cam, a Edelbrock performer 4 barrel intake/edelbrock 600cfm carb, and recurved HEI dist. Usually that combo really perks up any engine, but this felt really lame. You could hear the 4barrel open, but not much happened. I just accepted the fact that its "just" a 8:1 307 and there isn't much I could do about it.
But man, when I took it out tonight, it feels really strong after opening the exhaust!!!
I know more flow is always better, but I didn't really think it would yeld real seat of the pants power.

Heck it even sounds louder! I was disappointed after the new duals, it has short magnaflow knock-off mufflers and 2.25" pipes, that it didn't have a little more bark. I was also pretty disappointed that the exhaust guys just stubbed the new pipes onto the old head pipes.....they didn't want to deal with old rusty manifold studs either.

I was supposed to return the truck to its owner Sunday. But now I feel I should pull the passenger side down and look in there.

I'd like to hear if other people have seen this too? I'd feel like an idiot if I hold up giving the truck back, have to drill and tap three more exhaust studs if its common knowledge that only the driverside had this weird restriction.

Pic of the truck. Its just a rough farm truck, but it would be nice to have the old 307 put the power down!