Just more convoluted than the earlier ones? Don’t flow as well?

Flow. Cat?

Probably the short primary tube design (like a manifold log design), with a long secondary (each bank) leading directly into a restrictive muffler/egr dump/ + cat. Everything the EPA/CARB needed in a '75-'76 914 to run hot and compliant
Nothing in this design bringing performance to the table.

And the fasteners rust up pretty solid. LOTS of piping out side of the casings. Less exhaust options.

The early 2.0 HE's are not headers but at least they're two pipes that go straight back.
Headers are the only true bolt on HP, although the increase isn't that big on a stock engine, on performance engine the difference using a good header is huge.

a cheap solution would be to buy set of steel heatexhangers with bad or no tin ,not worth much,then bolt on stock or aftermarket muffler.
Those pipes are not efficient and it will cost you $$$ to get 3 bolt flanges made,good luck.

Thanks all - very helpful discussion (as always)

I have a box full of 75/76 flanges, laser cut, they look great. Pipe is fairly cheap too. If you live somewhere you don't need heat.you can turn the header pipe around from side to side, make an extension to the stock location and just buy a exhaust for a 75/76 car.
If you want heat, swap out the cat for a extension as well,and buy the proper exhaust.
Triad makes exhausts for any stock 914, 1.7/1.8, 2.0, 75/76 and for the 914/6.

Sorry I missed this post @Triaddave .

Thought this might be of interest to people who have an opened up a set of 1975/1976 he exchangers, here’s what they look like inside.
Click to view attachment