340 exhaust manifold vs stock 318

My TTI kit came with an H-pipe. I never gave it much thought, until I had to cut it out to fit the GVod. I was running a 4-speed with a starter gear of 2.66x3.55=9.44, and already had a pretty torquey engine with 10.8Scr and a [email protected] cam
But with the H-pipe gone, I immediately felt the loss at take-off. I worked my tune all summer and never got it back. My cure was the 3.09low Commando box, for a new starter gear of 3.09x3.55=10.97, and I have been running that way ever since. That 3.09 is plus 16% over the 2.66, so I suppose there was a lot of torque in the H-pipe. I don't miss it any more cuz the combo does real good without it.
As to the collectors, I read that Yunich material too. But I had no choice in the collectors after I ordered the TTIs and dual 3inch pipes. I got what I got. I didn't order the 3inchers because I imagined I needed them. I ordered them for the heat sink they are. By cooling the exhaust off before it hits the mufflers, I reasoned that they would have less trouble navigating thru 3 pass mufflers. And then they can fall out the 3" tailpipes without having to be pumped out. That was my reasoning. I have nothing to compare it against so IDK if it worked. But the car went 93 on the only successful Eighth-mile pass it ever made, now with a 230*cam. Ohchit, that pass was made without street exhaust, just the 12" collector stub,lol. But it didn't feel any different without the system.
As to the sound; I can't comment, as no one except my son has ever driven it, and he won't run it like I do. Plus I got no before and afters.
I was too young in the sixtys to get onto the track, and too broke in the seventies, and the babies came in the eighties, yada,yada . But thru it all I almost always had a strong streeter.Mostly 340s, occasionally 360s. I tried some stuff on smogger teens but mostly it was a waste of time. At 8/1, I couldn't get enough bottom end out of them to run the street-friendly gears, and they always needed at least a 2800TC. With 4.11s and a clutch, some days I smiled. After my first 360/clutch, I never went back to less. Lessee, that was maybe 1976. Well not quite true, I did have a tired 340/clutch car I bought in 78, that I was gonna put a 360 into.... but then the babies started coming, and the car went into storage, where it rots to this day.
True duals do wake up a 318, especially with the 340HO logs.... and 340 valve springs,lol. But it's kindof subjective;and with hiway gears, I never noticed any power increase except when downshifting to pass, on the hiway. But I sure noticed a torque loss at the bottom, whenever I installed a 340 cam. To this day I have three or four of those cams kicking around.

A cammed up 427 in a Javelin eh? sounds killer.How'd you like that wheelbase,lol. I cannot imagine that at speed.