Quote:
Originally Posted by Dave80GTSi
I agree with your philosophical points above, but in my opinion the benefits which you note above are pretty much moot for a car which will be driven primarily on the street. For a track car which lives at high rpm's, definitely, but for normal stop and go / freeway driving I genuinely doubt that you'll see any differences.
What you did not mention: Where the stock early tube manifolds shine are in their flow advantage over the stock 3-in-1 cat manifolds.
Wanting to replace my cat manifolds, I did not even consider aftermarket headers since I've wasted far too many hours of my life already struggling to make various aftermarket headers fit a variety of engines. Sometimes you get lucky and they fit well; other times you curse and swear and beat them up with a hammer. So, I found a pair of these early tube manifolds, Jet-Hot coated them, and used them:
These early manifolds have individual runner I.D.'s which perfectly match up to the head exhaust ports, so I fell that the gas flow potential is not compromised too much by their lack of a collector - again, for a street driven car. I consider these manifolds to be 'poor man headers', but for me their key advantage is that you know that they will 100% fit perfectly. Plus, they are more compact width-wise than are most splayed tube headers, which should serve to keep heat away from such things as power steering hoses and the valve cover area.
By the way - It's probably too late for you considering your broken bolt trauma, but I would have recommended that you replace the old broken bolts with studs and nuts. Your car's future owner would have thanked you:
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Definitely agree, the power benefits will likely be minimal but the theory behind it is there. I do use this car primarily for mountain driving where I am consistently in a lower gear and use the entire rev range pulling up hills so I might see some benefit. Either way, I’ll be replacing the rest of the exhaust in the next year or so to open it up more (high flow cat and muffler) so the headers were really just to remove a potential point of restriction.
That catted design is truly awful for flow so I definitely see why you went the direction you did. Looks great!
In terms of fit, the fitment on these was actually pretty good, so maybe i got lucky there but there is a surprising amount of space to work with. I did have to zip tie one hose out of the way and added some heat resistant tape to make sure there aren’t any issues.
While I’m back in there I’ll definitely consider the stud/nut option. Is the primary benefit here just less risk that you’ll snap bolts down the road?
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