[raidex1]

I removed the old headers from my 68 GTO and I want to go to stock exhaust manifolds. I see Summit has some nice ceramic coated ones by Hooker but not for my car. Does anyone know who might make stockl looking exhaust manifolds ceramic coated?

[67GTONUT]

http://www.ramairrestoration.com/rm-...y-headers.html

$570.00 with Ceramic Coating....

[Blued and Painted]

Mock up some factory logs with down pipes, get things fitted the way you want, then send them off for ceramic coating. There are normally one or more coating shops in major metro aria's. Jet Hot comes to mind.
https://www.jet-hot.com/

Testing show little or no performance gain with headers over log manifolds in stock or near stock applications.
http://www.hotrod.com/articles/hppp-...-vs-manifolds/

I personally like to open up the outlet of the logs from 1 7/8" to 2 1/8" then use mandrel bent down pipes.

[mklinger]

Send them off to Calico Coatings in Denver, NC. Probably about 200 to coat them.

[b-man]

For myself I'd skip the ceramic coating and bead blast a good set of factory log exhaust manifolds and apply POR-15 exhaust manifold paint. My experience with it was great, still looked really good after 5 years and 30K miles of street use.

The POR-15 manifold paint costs about one-tenth of what ceramic coatings cost. There have been mixed reviews on the longevity of the professionally applied ceramic coatings.

[fairwayhit]

Seems like that Hot Rod article saying that stock manifolds are almost as good as full length headers, is referring to the RARE exhaust manifolds (not log type manifolds). I have read quite a bit online saying that there is a large advantage to using the RARE manifolds or Headers.

Will just opening up the outlet of the logs be similar? I was leaning toward getting some of the RARE manifolds (unfinished) and using some POR15 on the outside of them. But, if I can get 90% there by just grinding on my logs, I would probably forgo the added expense.

Any opinions?

[Sirrotica]

Many years ago on my 400 67GTO dirt track car (1976) I replaced the log manifolds with RA III manifolds and the seat of the pants dyno definitely registered a positive result. Due to class rules only cast iron manifolds were allowed.

I realize that there have been article that say that the logs are good on a street car and not too much gain will be made. One has to ask, if the logs are only somewhat less efficient, why would Pontiac spend all the time effort and money to build the RA manifolds?

Pontiac has been making efficient cast iron manifolds since 1959, I believe. They do make enough extra power through efficiency to the exhaust side of the engine and are worth the investment if you want to stay with cast iron. Unless there is a restriction that I can't use headers, I will always go for the best alternative, long tube headers on my own cars.

[b-man]

Swapping from log manifolds to the Ram Air/HO manifolds, at least the A-body and 2nd-gen F-body design, nets you around an 8 HP gain over the logs on a stock or relatively stock engine.

The long-branch design used on 1st-gen F-body and '65 -'69 B-body cars are more efficient than the shorter A-body design, so those I'm guessing may net you as much as a 15 HP gain. However keep in mind you must use whichever design fits your chassis, so you can't pick the long-branch unless your chassis will accept them.

The more modified the engine, the bigger the gain from the free-flowing RA/HO design.

So you must decide whether or not it's worth it to gain 8 HP on a stock engine for the money invested. Costs approaching $500 for the shorter A-body design or close to $650 for the long-branch once you add in the cost of new down pipes required for either set and the oil filter angled adapter needed for the long branch.

Simply opening up the outlet on the log manifolds won't make them equal to the RA/HO shorter design manifolds, that's mainly a cosmetic 'feel-good' mod more than anything. I've done it myself to make the outlet size match up to the inlet of the down pipe better, but people who have actually dyno tested that mod say it doesn't register any gains on an engine dyno. Can't hurt though.

The biggest bang for the buck for a near-stock setup would be to retain the logs and upgrade the down pipes to a set of aftermarket 2-1/2 mandrel bent pieces to eliminate the big restriction present at that juncture. Doing that along with a good low-restriction mandrel bent exhaust system will probably give the most performance for your dollar.

Upgrading to the RA/HO manifolds is fine as long as you're aware of the cost/performance benefits. Some guys upgrade simply because they look cool, there's nothing wrong with that thinking either.