So I cashed in some company stock...time for MOAR power

[IcePickFreak]

http://forums.corvetteforum.com/c6-tech-performance/2238116-1-3-4-vs-1-7-8-header-swap-results.html

This guy PowerLabs did the 3/4 to 7/8 swap to test on his SC LS2. He said, "Conclusion: The 1 7/8" headers gave up *nothing* in the low end, in fact gaining a small amount of torque, while maing slightly more power. If you aready have 1 3/4" headers, and are making similar numbers, spending the money to "upgrade" to 1 7/8" is not a good investment given the minimal gains
If you have a F/I car, or are thinking of going to F/I, there is no reason not to get 1 7/8" headers, given the extra power with no trade-offs
If you have a F/I car making a LOT more power than me, you stand to gain a LOT more from the header swap, since smaller primaries will always "max out" sooner. That said, 600WHP does not appear to be the point where they max out."

Basically there's not much difference between the two but if you're buying new, there's really no reason to go with 3/4 unless it's cheaper.

Right, except again this is at WOT, and with a supercharged car on top of it. Since it is supercharged, I'm actually surprised the 1-3/4" kept up that close at WOT. Kinda worries me that he says F/I (ie, supercharged or turbocharged) and not just supercharged though. You're not going to be running longtubes with a turbo(s) lol. I'd still give up 5 peak hp & ft-lbs at WOT for better part throttle response for a daily driven car that would see way more <2k rpm partial throttle action than >5k rpm WOT.

And I hope I don't sound as I'm arguing, it really comes down to personal preference and what you think is best. It's not going to be a night and day difference between the two either way. I've seen this argument going on for years on LSx forums and it's ongoing to this day and probably will be when they move on to the next gen smallblocks. Just giving my view & personal experiences after having several cars with longtubes in the past, do with it what you will.