805moparkid - What is your thing with larger header tubes? I am not trying to attack you or anything like that because I read your post all the time and you have a lot of great knowledge. I just am wondering. If you have some articles on proper header tube size then I would be really interested in reading them.
If he was building a race motor and was looking at proper tuning of everything then header tube size is a big factor but if he just wants a little more power and to be able to run a better exhaust than header tube size is not going to matter that much unless its too small. I am not saying bigger tubes are better but it is better than being too small.
That makes sense to me and I guess with the slant being a torque motor then correct sizing would be a bennefit. Thanks!
go to slantsix.org and talk to the slant six guru himself, Doug Dutra.
From what I can gather, they don't crack like the factory units. And they should have an increase in performance because theres more room for air to exit. He does make them to fit stock intakes too I think, but you should upgrade to a super six setup (two barrel from the mid 70s).
Thats pretty much my plan as well with my DD 64 Valiant wagon, but mines a 3 speed stick and I will probably leave the stock exhaust manifold alone for now. Funny thing is, the super six setup will increase you mpgs too!