Does anyone KNOW the difference between SB HP Exhaust Manif

[73DartSport340]

Is there a BIG difference between HP exhaust manifolds(68-70) and the 73 manifolds that came with my 340. Seems like I get a lot of answers ranging from a LOT of flow to just 1-3/5 HP . If its just 1-5 HP I would not waste the $$$ on HP manifolds. I was looking for actuall tests or test results becuase ive gotten so many differing oppinions I don't know which is right but at least with actuall test/dyno results there would be something concrete to back it up. Someone had said Mopar Muscle did a test(between stock 318 manifolds,later 360 manifolds,HP manifolds,Shorty headers and full headers.) but I cant find the test anywhere.

 

[GotDart]

This is the article you're looking for.

http://www.moparmusclemagazine.com/techarticles/155_0307_exhaust/index.html

 

[73DartSport340]

Thanks man that was the exact article! I was thinking of going back to manifolds when my headers that are on it now rust through. I was wondering if it would ne worth it to go with HP manifolds over the 340 1973 Manifolds that came with the car. Looks like at my power level(I have Aeroheads heads J heads I think with a valve job but no porting, the larger Summit SB Mopar cam I think it has a .441 lift but cant remember the other specs but its not "big", a eddie 750 carb, 727 with a shift kit,8 1/4 rear with whats probably 3.21 gears. So I think im relatively mild enough that the whopping 1 HP they gained over the 73 340(and later) manifolds would be money wasted unless I already had a set laying around....why not just use whats already free and I have. Thanks that really helped my decision become easier.