Tune will fix it. Mine had lag after the HFCs and the tune fixed it.

Yea, I figured the headers would sacrifice torque without a tune. Still debating about getting them.

NISMOZ, did you leave your headers alone and simply tune with HFC and exhaust?

Berk HFC is under my desk and mid-June ETA for my F.I. exhaust. Tony at F.I. is experimenting with different configurations than the G37 like eliminating the H pipe and going for true dual at the mid section (I think). More variables there...

From your posts, it appears you've had significant gains from HFC and exhaust. That's all I'm thinking about doing besides debating about headers and keeping the stock airbox... last is UPREV.

Seems the common trend in headers.. I look at headers as a torque-adjustment tool on an engine. Rarely do you see poorly designed headers on factory cars anymore, they are probably one of the only well-thought and designed pieces connected to an engine. It's the balancing point or translation of power if you will. Toying around with headers usually will just shift power from one point and place it somewhere else, rarely does anybody see gains by using them these days.

I installed headers on my previous WRX and the same thing happened.. despite the vehicle being turbocharged, it still robbed torque and gave a very discrete bump in HP between 6000-7000 rpms.. To further make things worse, my friend had the same experience and he hated the headers so much for the torque loss (and that it completely removed the burbly sound of the boxer engine because the headers were equal-length instead of odd-length) that he put his stock headers back on and said the car was so much more streetable because he had his bottom-end torque back again.

I think i'll stay away from headers until Stillen decides to release some generation2 models and invest more time into the development.

-Div

Those are some very impressive numbers. 317 whp on Shariff's heart-breaker in impressive considering what others usually do on that dyno.

would installing headers on a 370z make the exhaust much louder? if so, is it a nice louder or bad raspy louder?

did u finally get that tune yet? if so, do u think the headers were worth it?

didn't make that much difference on mine... cats and muffler on this car seem to make more difference... if you want real loud, straight pipes... resonated if you don't want raspy

how do u like ur headers? it seems like semtex wasnt very impressed by them, at least before he got a tune, do u know if he got a tune with his headers yet?

i think there are some dyno testing results around here somewhere... i recall they are worth a few ponies... as far as bang for your buck on power upgrades, it is definitely not the place to start, as I think most would agree... otherwise, they are very shiny, pretty, and add a bit of character to the sound (but not big db gains)... you should also be able to find sound clips in the exhaust sound clips thread... if you have the extra dough, go for it, otherwise, spend elsewhere

does it really matter that their shinny and pretty since u cant see them anyways when installed lol. did u get a tune after ur headers install? im wondering if a good tune will use the full potential of the headers?

I haven't gotten a tune yet. I'm waiting for UpRev to release their stuff. As for the headers, if I had to do it all over again knowing what I know now, I probably wouldn't. How's that for brutal honesty?

Same thing happened with my last car. I purchased some headers and had them installed and the low end torque went bye bye. It really did suck there was only a small power increase and that was above 5000rpm. I took them out within a month and my cars reponse was much better.

Not to say that headers can't make a car better but I think what has been said above is pretty much dead on for most vehicles these days.

I don't think the headers are a negative. And with tuning they may turn out to be more positive than they seem now, too. It's just not worth the installation hassle (or cost, if you're paying someone else to do it).

That's true. They may pay dividends with a tune. It'll be hard to tell though, because one would need to do a tune w/o headers for a baseline, then do another tune w/ headers to get a comparison number.

on my sentra ser spec v, after i installed my header it made quite a bit of differance. install was pretty easy too, which is to be expected on a 4 cylinder. didnt notice any torque loss and noticed a gain in hp. maybe because the stock exhaust manifold on my sentra is so much shitter than the exhaust manifold on the 370z?