Header mod or no?
 

I currently have HFC, Greddy GT Evo catback, Z1 2.5" intakes & a tune and my output is 300whp 264 wtq. I find my car to be on the loud side while I do not get bothered by law enforcement yet for that matter, although I got used to the drone and noise inside the cabin. I'm looking for more power but I can't justify going forced induction since I rather keep that kind of money for a brand new muscle car for 2022 or 2023. I would like your input on what could be done to increase the power while not getting raspy or obnoxious loud. The car is mainly used for spirited driving and casual street racing.

You could go with the following:
1. Dewala air intake guide
2. Three inch intakes, but you'll need a retune
3. Port and polish your throttle bodies
4. Upgrade your throttle bodies with the Daytona throttle bodies, but you'll need a retune
5. Swap out your upper intake manifold to a Motordyne or Z1 model, or have yours ported and polished
6. Port and polish your lower intake manifold or upgrade to a Z1 model
7. Light weight / under drive pulley (I know there are mixed opinions on this, but it is an option)
8. Consider a better cat-back set up
9. Delete the HFCs and get test pipes (you'll increase rasp)
10. Upgrade the cams, but that's expensive and labor intensive.
11. Like you said, you can upgrade the headers, but your drone and rasp may increase. I can't speak to this because I haven't upgraded them........... yet.

I can't think of anything else right now, but if I come up with anything, I'll respond with it.

You can always go with e85, but the gains won't be nearly as high as a FI engine with it, but it is an option. If my memory serves me correctly, I think people have gotten around a 25-30 hp gain with this on a N/A 370Z.

You'd be better off spending the money re-gearing the rear end over spending thousands of dollars to get 25-30 whp.

http://www.the370z.com/forced-induct...rous-370z.html

Only way I can see being the same noise level and not messing with the internals.

Honestly any more mods past what you have aren't worth it. I wouldn't spend more money on anything but injectors to run E85 if you have that available locally. You can probably make 320whp on E85 with a good tune w/ your current mods. Going from 320whp to 350whp will cost you as much as FI and it will still be slow.

Staying naturally aspirated will cost you a small fortune and is not worth to most. I would not do anything else past what you have done to your Z already. Save up for forced induction and go that route if you really want more. Nitrous oxide is one of the best bangs for the buck and can be safe to use. I would go with nitrous kit on your Z!

A lot of us ask ourselves this same question at one time or another.

Wish I would have seen this a couple of months ago when going CAI. The intake temps. are exactly the same as my well insulated under hood open filter elements and don't cool off any faster when in motion. :shakes head:

Wonder if it can be done without removing the bumper cover.............again. :rolleyes: Considering my '10 Base bumper cover radiator inlet slats are deleted, it seems it may fit through the opening.

If you already have HFC, no sense in spending $ on headers. You will not gain much from where you are. You can do it and and convince yourself there is a difference. Ya, that's just you justifying the spend. Go with gearing instead......4.08 and re tune. You will enjoy this better.

that sounds like a quitter mentality :roflpuke2:

I thought the same until I did the common mods (HFC, intake/exhaust, tune) AND bigger rear end (gears) and it's definitely worth it! Shut up with your generalizing suggestions!

With bolt ons and tune + gear, the 370z is easily a 12 second car which isn't slow.

Interesting, I'm NOT on e85 and its on UpRev making... look at my sig.
I'm not even looking at E85 options until I go boosted.

If I add the M370 intake mani and retune on Ecutek, 335+whp should be doable with my Tuner.. again, without E85.

It's because you guys already have the good gas (93? 95?)

Over here in california, we have watered down gas. So E85 will be felt more for us

Yeah, good point that's true. Cali has 91oct so I guess in Cali upgrading to E85 would be beneficial.

93oct here btw.