I went back to your original post. Do you have a set of Edlebrock aluminum heads? What size carb?
If you have the aluminum heads, you should have noticed a large mismatch between your exhaust manifolds and the exhaust ports on your heads. The heads exhaust ports being noticeable larger. If you use the hypo exhaust manifolds, you should part match them to the heads. You can do it yourself with a high speed grinder. The JBA shorties are already large enough for the exhaust ports. But they are a bit spendee in comparison to the hypo exhaust manifolds.
Power is all about tuning. I would submit that the horsepower gains from stock to hypo would be measurable. The difference between the hypo and the JBA shorties would be a bit in the favor of the shorties due to larger passages. I would bet the tri “y’s” would be a bit better than the shorties and the long tubes would be best of all. But tuning is the key and without a dyno near impossible to tell which set up is the best.
There is a fallacy in my mind about long tube headers. People think that they are top end only. There have been many header comparisons tests in magazines and on mildly modified motors long tubes and most results show that long tubes are the best across the board as long as the tube size is a constant. Your motor based on what I have read and experienced would work great with either 1 and ½ or 1 and 5/8 primary tubes and 2 and ½ exhaust. The “blackjack” 1 and ½ headers I mentioned will need some porting work to match the exhaust ports of Edelbrock heads. And there is little to work with. So based on that I would go with 1 and 5/8 primary tubes on any header selection.
Tri “y’s” would be a great choice also. In tests I have read they perform just as well as long tubes down low and only sacrifice minimally at top RPM. And they may fit better!!
You have done enough work to your motor, that if it was mine, I would go to tri “y’s” or long tubes. Find out which one works best with power steering. If you motor had stock heads I would recommend the hypo manifolds. Even a mildly built motor with stock heads work great with the hypo‘s and the shorties. The shorties are a great pick for any motor with bigger exhaust ports and strokers for low end mid range and also sacrifice only a bit above 5,000. If you never plan to go above 5,000 rpm the shorties or the tri “y’s” will work great.
I own a 302 with Elelbrock aluminum heads that I am stepping up to a supercharger on. The JBA shorties (not trying to sell them to you) will be for sale and I will go to long tubes as I want it to be all it can be.
Again, my opinion only based on what I have read and experienced.
Rob
