Quote:
Originally Posted by Modernmusclecar
....just dont straight pipe it and cut off the cats. Thats the real issue in regards to loud exhaust and no cats.
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Glad to hear you agree with me!
I've built a few cars from the ground-up and owned a shop. Then got an engineering degree and used Ricardo Wave to design manifolds as one of my projects.
Older log-style manifolds were really bad, well worth replacing as the entire goal was to lower costs, even at the expense of fuel economy and performance. Now fuel economy is such a big deal it's going to be MUCH harder to improve on a stock manifold unless you make significant changes to the motor, like a different cam or forced induction. IMO, unless you are making those major changes I'd definitely leave it stock. In many ways the emphasis on fuel economy pushed a lot of the massive improvements we've seen in performance vehicles, as many of the things that make power also increase efficiency.
I honestly wouldn't be surprised to learn that pre-emission era vehicles used to be purposefully designed to waste fuel, then when emissions standards became a thing those requirements were often at odds with fuel economy and performance because technology wasn't developed to adequately meet emissions, so you had bodges like obstructing intake and exhaust ports in weird ways (TBI injected motors), which massively handicapped the motor. In these cases you could do mods and get significant increases in both economy and performance, and while it may not strictly meet emissions it could be argued that car ran so much better with the mods that it's well worth it.