would these 4 mods add to my 2004 AT coupe? Any feedback appreciated!

STILLEN HI-FLOW INTAKE WITH STILLEN Z-TUBE

MOTORDYNE 1.5" Isothermal Spacer Kit 350z, G35 03-06

DC SPORTS HEADER: 350Z 03-06/G35 03-06 (CERAMIC)

STILLEN CAT-BACK EXHAUST SYTEM DUAL WALL: 2003+ G35 COUPE

The intake is pretty much purely a sound mod. you might get 1hp out of that.
The spacer well motordyne doesnt make a 1.5" spacer lol. Im assuming your talking about the 1/2" spacer. You may get 3 or 4hp from that.
The headers and exhaust again your problem looking at between 3-5hp.
All in all your looking at 10-15hp gain

Moved to Engine/Drivetrain.

I think ^^^ is dead on. You might pick up 20+ between 4k and 5k, but at peak, less than 15hp.

i'd like to see this 1.5" spacer.

How do these companies get away with claiming such high HP gains when actual gains aren't even close.

Bolt on NA mods aren't really worth it financially if you're looking to make some significant power. FI is the only way to go.

Many of these aftermartket modifications do indeed make pretty good power, in isolation. However, they are not additive.

If you have a bone stock car, and put on a pop charger, you might pick up 6hp at peak. If you have a stock car, and you put in a spacer, you might pick up 8 to 10hp at peak. But put them together, and you might only pick up 8 to 10hp at peak.

^^Makes perfect sense. Thanks!

StreetChase,

3-4 HP? That's way off. Where did you hear 3-4 HP?

Install one on the dyno to see what it really does. Or simpler yet, do a search here for any one of the numerous independant dynos performed on them.

Tony

PS the link in my sig below is an independant test comparison of several plenum mods performed by "Sport Z Magazine" --> now known as "Nissan Sport Magazine".
It's 100% independant.

And +1 to trey. They commonly add 8-10 HP at the peak and commonly add 11-13 HP at redline. Its the real deal here.

So are you saying he's under estimating or overestimating?

Seems like average gain across the power band is around 3-5hp. Only at very high rpm will you get around 11-12hp. Average gain is much more important to me since during the average day I see >5000rpm maybe once. I'd like to see a product that actually improves low end torque on this engine. Not knocking your product, I'll still buy one, but 11hp between 5500 and redline isn't ideal.

As in Trey? Neither. That's why its a "+1".

Average, yes, but no mod lifts the power curve equally across the board. Bolton's are always referred to their max gain or delta. And this is also under the assumption that it is being advertised truthfully. I'm sure you've found many manufacturers don't.

Yes, it would be ideal to have a average rating within a given RPM shift range. But this is also why I show the bar charts and plots showing average gains from 3rd gear redline to 4th gear redline. This is the area or range most commonly used in road course racing. ...And drag racing to a slightly lesser extent.

But when was the last time you saw any one produce such an analysis? With the exception of the MD website, and as far as I know of, mods like this are always rated at "max delta". This is the conventional standard and is reasonable as long as its true. And I can go with average gain from idle to redline as a standard as long as its called out or specified. But the usual industry convention is max delta so I go with that.

EDIT: And I do wish the industry standard was "average gain" but that is "ideal" and as such, will never happen.

My sedan dynoed bone stock at 214HP. Everything you see in my sig except the reflash resulted in 235HP (same Dynojet/SAE corrected). I never dynoed post-reflash because the shop got amnesia about a free run afterwards so I told them to stuff it (lesson: get it in writing). My best guess based on the butt dyno is 7-10HP gain (yes, it was that dramatic) as the AT sedans definitely have the most to gain from timing/fuel tune and I was way lean causing timing to be pulled.

So I would estimate being at 242-245, or 245/.8 (20% loss) = 306 crank. My goal was to try to get close to 2007 #'s then quit. I have quit.

So dont expect too much as far as dyno numbers, but it makes the car more fun for sure. When I drive first gen loaners, I can't believe or remember my car being that slow/boring. N/A mods are worth doing if you like the car enough to keep it for a while. And whatever you do, a tune is pretty much mandatory to bring it all together.