I don't think it's as simple as "makes more torque". I have heard people who claim to know such things claim that a Tri-Y typically takes effect lower in the RPM range than a 4-1. To me that means I'd want an LCE for hill climbing and drag strip racing, and a Thorley for rock crawling and putting around town, but for the tiny gains we're talking about with the 22RE I'm not sure it matters much either way?
You're right, there's not a huge gain in hp/torque with just a header, but a good combination of header, exhaust size, and if you're able to get away with it, the removal of the cat, you can see a good amount of gain in power over stock. What the exact hp/torque numbers are, I have no idea as I've never thought of dyno'ing my truck before and after! I will say that given the low, stock hp numbers (what's stock? Something like 110hp, right?), going up by another 15hp does indeed make a big difference in how the truck runs.
And I agree, just saying it "makes more torque" is just a generalization, but if anyone's interested in how a tri-Y header works vs. a 4 into 1, there's a ton of articles on them all over the place, some are very technical and show actual data in their tests. From what I understand, the tri-y scavenges better in certain rpm ranges than a 4 into 1 would in that area, but the 4 into 1 does better at higher rpms because they supposedly flow more freely.
I have had both and will still make the claim that the tri-y works better with my 22RE than the 4 into 1 I sold many years ago. I've played around with my other friends who have 22RE trucks/4 runners, and aside from one of them, I could literally walk away from them while going uphill in 4th gear! I do have a lot more done to my engine than most people too, so as I said, its a combination of things I've done.
One other interesting thing I have noticed is the amount of power lost with a cat! I'm not encouraging anyone to go out and pull their cat off, but for me, I've run without one and IMMEDIATELY notice a difference in how it pulls away! I have also noticed that when I had the cat out, I gained almost 2mpg on a long road trip than when I had it in on the same trip. I've since found a hi-flow cat that seems to work okay, although it still doesn't have as much seat of the pants pull as without running one!
Maybe someday I'll find someone who has a dyno that's willing to give me a few runs! I would definitely be interested in the actual numbers! I know for a fact that going from the stock header on my supra at 148hp, I have the dyno sheet somewhere at 176hp with a thorley on there! Of course, that's an inline 6 and the whole exhaust was changed out at the same time the thorley was installed, along with adjustable cam gears and several other things!
Yeah, I know! Not an apples to apples test!!! :bounce: