Tuning will always prove to give gains as the car isn't running as efficient as it was tuned for when it was stock. So adjusting the A/F ratio to the new mods will definitely help.

i think some ppl are looking at your installation as kinda a fail, which I believe its not. it did gain you hp, and that was the goal right? I do agree that its a PITA installation for as much hp as you gain for intakes, but a gain is a gain. congrats, and i cant wait for you to get a tune!

You'll see gains, but then again you'll see gains with a tune without the headers.

I really don't see the point of doing headers on the HR or VHR. They are already equal length from the factory; and the fact is that the engine is not going to benefit from larger diameter manifold piping; not NA at least.

Semtex don't worry, I am doing mine for sure to either back-up or negate your results. I will be doing it with the full stillen setup to see what happens to the numbers. The point is to get more power out of the car no? I think you have successfully done that and at the end of the day 11whp isn't so bad. I think we will benefit from having the headers once we get into tuning. With the stock tune, we may have lost backpressure and lost a little tq, but once we are tuned and we are flowing more air through the system, we will benefit from the extra flow. Meanwhile those without the headers will suffer a little from the obstruction. I think without a tune, the stock ones are pretty dead on the necessary flow. With a tune, the upgraded ones will be dead on.

Yep, I agree. I don't think it's a fail at all. The results may be a little underwhelming, but I think that's just because we've seen such insane gains from all the other bolt-ons up to this point. But let's be realistic here. Getting +18hp from intakes is insane, and getting +11hp from headers, while not as impressive, is still a very decent result. Or to put it another way, if we feel disappointed at the results from the headers, it's only because we've gotten a little spoiled. I agree that we should greatly benefit from a tune, and we'll find out for sure soon enough. Sharif said that he expects UpRev to have their software ready for the 370Z in about 2-3 weeks. He also said that he estimates he'll be able to get another 15 whp out of my car. Time will tell!

nice numbers!!!! now some track time?

324.6 WHP & 263.94 ft/lbs TQ (DynoJet)
holy crap, ur at the whp that others are seeing to the crank!

Now that you have installed all these goodies what are you getting for mpg?

15.4 mpg - about what I was getting before.

I'm curious regarding about your numbers. They are different types of dyno machines out there, which one is more accurate? Is the dynojet that u used pretty accurate?
I read on this forum that certain dyno machines aren't very good. I just can't remember what the name is. But I've heard dynojet on this forum and I think some said that it's not very accurate.

Accuracy isn't a big deal as long as you use the same dyno and get baseline numbers first. It's easier to just compare gains (and losses).

I just looked at the dynos in detail for the first time. I have to say that headers are totally a waste. I know that's gonna piss some people off - sorry about that.

First, I find it odd that the dynojet showed so little change yet sharif's dyno showed such large gains(comparatively). Dynojets might not be the most tuner-friendly brand of dyno, but they are generally exceedingly consistent.

Unfortunately, the only graph you have that is overlayed is the torque graph. Looking at that plot, you don't start making any more power than before until about 6750 rpms. That means that in the real world, you won't see any difference unless you spin the piss out of the car. Realistically speaking, you'll see a very small(10whp) difference, and that will be for less than 1000rpms. That kind of gain won't be perceptible until you reach something like 4th gear, where you're actually gonna be in that range for more than a split second.

I agree, actually. But the big unknown is what happens once a tune comes into play. Will these headers 'come alive' and yield significantly more gains with a tune than would be seen if I just had the stock manifold? If so, then it's worth leaving them on. If not, I'd just as soon take them off and have the stock manifold put back on, because as things are right now, I think the car was more enjoyable to drive with the stock manifold. In other words, if I wasn't planning to get a tune, it'd be a no brainer. But I am planning to get a tune, so now it's a bit of a gamble either way. Wish I had a crystal ball right about now.

Are you getting much of a "lag" response with half-full throttle past 3-4k rpm? I'm still stock, but that's what I feel under 3k RPM on up under half throttle (still breaking in).

^No, not past 4k rpm. But up to about 3500 rpm, the lag you're referring to has gotten a little more noticeable. See, I've lost a little low-end torque with these headers. Now, that's to be expected, because the backpressure has been reduced on account of these headers flowing a little more freely. But usually that loss in the low-end is made up for by gains in the rest of the rpm range, hence it's a fair trade off. I have no such gains, at least not any significant ones. My thinking, however, is that it'll be good to have these on when I get a tune, because like I said, I've lost backpressure because these flow more freely. Better flow usually means more room for gains via dyno tuning. I think I'll be glad I installed these in the long run, once I get a tune. Keeping my fingers crossed anyway.