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Specs are compiled from manufacturer listings and verified buyer reviews and can change over time — please confirm the key details on the product page before buying.
The VQ35 engine in your 350Z gets heat-soaked, and that hot air costs you throttle response. A plenum spacer lifts the intake plenum off the engine block, creating a thermal break and adding a bit of volume. The best 350Z plenum spacer does this without robbing you of low-end torque or complicating the install.
I’m Min — the founder and writer behind Gadgets Feed. This guide is built by comparing the manufacturers’ published specifications and the patterns across verified customer reviews, so you get each pick’s real strengths and trade-offs instead of marketing spin.
Here is how to cut through the options and pick the right 350z plenum spacer for your build and budget without buying twice.
Our Picks at a Glance
How To Choose The Best 350Z Plenum Spacer
Every spacer on this list does the same basic job, but the differences show up in material, thickness, and fitment details. You want the one that matches your engine version and your tolerance for extra steps during install.
Understand the Non-RevUp vs RevUp Split
This is the first filter. The VQ35DE in the 2002-2006 350Z is the non-RevUp version, and that is the engine most of these spacers are built for. RevUp and HR engines have different intake designs, and several makers explicitly say their spacer will not fit those. If you have a 2007-2008 car, check the fitment note before ordering.
Match Thickness to Your Goals
A 5/8-inch gasket is the common middle ground, adding volume and a thermal break without forcing you to relocate much. A 5/16-inch spacer is slimmer, which keeps things closer to stock and eases fitment. Thicker spacers can interfere with the front strut bar, so if you run one, confirm clearance.
Pick the Right Material
The material determines how well the spacer stops heat transfer. Aerospace thermo-polymer composite and thermal polymer are the descriptors used here, and both aim to keep intake air cooler. That cooler air is what improves throttle response and can add a few horsepower, though real-world gains depend on your whole setup.
Quick Comparison
| Model | Best For | Gasket Thickness | Weight | Engine Fitment | Amazon |
|---|---|---|---|---|---|
| Skunk2 Composite V2.0★ Best Overall | Max Performance & Volume | 5/8″ | 2.2 lb | 3.5L VQ35 | Amazon |
| Blox (BXIM-40200) 5/8″ | Balanced Performance Value | 5/8″ | 2.1 lb | 350Z / G35 | Amazon |
| Blox (BXIM-40201) 5/16″ | Easy Daily-Driver Install | 5/16″ | 1.65 lb | 2002-2008 350Z | Amazon |
In‑Depth Reviews
1. Skunk2 Racing Composite V2.0 Plenum Spacer
Our pick — 4.5★ from 30+ verified ratings; the strongest balance of quality and price.
The thickest, most aggressive spacer here, built for owners chasing every last bit of intake volume.
The Skunk2 is the heaviest pick here at 2.2 pounds, 0.55 pounds more than the slimmest Blox. At 2.2 pounds it is the heaviest pick in this lineup, sitting 0.55 pounds heavier than the slimmest Blox option. That extra material comes from a thicker 5/8-inch gasket design that adds plenum volume and creates a bigger thermal break under the intake.
Skunk2 claims this spacer lowers intake temperatures, improves throttle response, and adds up to 10hp, plus a fuel efficiency increase of more than 2mpg. The construction is an aerospace thermo-polymer composite, which is the material doing the heat-blocking work. Buyers report it fits great and installs easily, noting a clear performance increase once fitted.
The trade-off is that this thicker spacer loses front strut bar use, so if you run a strut bar, this will not work without modification. A few owners also mention the inner spacers for the top plenum bolts run slightly small, though they are drillable. One owner hit a fitment issue on an Infiniti G35X sedan, so double-check your engine version before buying.
What Wins Owners Over
- Aerospace composite blocks heat transfer well
- Biggest claimed power gain on this list
- Smoother, less restricted engine sound
- Includes all necessary hardware
What To Plan Around
- Kills front strut bar fitment
- No instructions included
- ECU needs a few days to relearn settings
Reach for this if: you want the maximum volume increase and claimed 10hp gain for a normally aspirated VQ35 build.
Look elsewhere if: you need to keep your front strut bar or want a simpler, more forgiving install.
2. Blox Racing (BXIM-40200) 5/8″ Thermal Shield Manifold Spacer
The crowd favorite that proves a 5/8-inch thermal polymer spacer can transform daily throttle feel.
The Blox 5/8-inch spacer wins on real-world results, with owners reporting noticeable power and quicker throttle response. Owners most frequently praise its power gains and build quality, the strongest consensus in this category. Buyers describe a lot of noticeable power and quicker throttle response, with one noting the install took about an hour.
It is made from thermal polymer, which provides dramatic heat insulating properties to keep the plenum cooler than the engine block. At 2.1 pounds it comes in just 0.1 pounds lighter than the Skunk2, despite having a larger 23 x 18 x 6 inch package footprint. It is explicitly ideal for the Nissan 350Z but not compatible with RevUp or HR engines, so confirm yours first.
Buyers consistently praise the Blox 5/8-inch for easy installation and solid build quality. The review pages sum it up: “A great mod for any vq35 engine.” The recurring gripe is the included bolts, which owners describe as cheap, and the lack of instructions. Plan to grab a tube of silicone gasket maker, since that is what the directions require for a proper seal.
Why It Is The Value King
- Strong owner consensus on power gain
- Thermal polymer blocks engine heat
- Includes bolts and spacers
- Fits 350Z and G35 cleanly
What Owners Flag
- Included bolts are cheap
- No instructions in the box
- Requires silicone gasket maker
- Hole alignment can need attention
Grab this for: a proven power and throttle response upgrade on a non-RevUp VQ35 without spending premium money.
skip it if: you want out-of-the-box hardware you never have to upgrade.
3. Blox Racing (BXIM-40201) 5/16″ Thermal Shield Intake Plenum Spacer
The slimmest, lightest spacer in this lineup, made for drivers who want a quick daily-driver nudge.
This is the entry point into the plenum spacer world, and its whole identity is simplicity. At just 1.65 pounds, it is 0.55 pounds lighter than the Skunk2 and 0.45 pounds lighter than the Blox 5/8-inch. The slimmer 5/16-inch gasket means less of a change to your engine bay layout, which keeps fitment easier for most stock setups.
It is explicitly compatible with the 2002-2008 Nissan 350Z coupe, but only the non-RevUp engine. Owners mention it fits perfectly with no problems and delivers a slight increase in power, plus a nicer intake sound. The manufacturer recommends searching for an installation video online and always wearing eye protection during the job.
The honest catch here is finish quality. One owner describes it as looking like a cheap 3D print copy and mentions not understanding what the small new parts are for. This is a functional budget pick, not a showpiece, so set your expectations on appearance before ordering.
Best fit for: a daily-driven 350Z owner who wants a quick, easy thermal break and a touch more intake noise without a major engine bay surgery.
Who should pass: anyone who wants the biggest possible volume gain or who cares about a show-quality finish under the hood.
Understanding the Specs
Gasket Thickness
This is the single most important number on a plenum spacer. A 5/8-inch gasket adds more volume and a bigger thermal break, which is why the Skunk2 and the Blox 40200 both use it and both claim stronger gains. The 5/16-inch Blox is half that thickness, making it easier to fit but more modest in its effect. Thicker is not automatically better if it costs you strut bar clearance.
Thermal Insulation Material
The spacer’s core job is to block engine heat from soaking into the intake plenum. Aerospace thermo-polymer composite and thermal polymer are the materials doing that work here. They sit between the hot engine block and the cooler plenum, which keeps intake air denser. Denser air improves throttle response.
FAQ
Will a plenum spacer fit my 2007 or 2008 350Z?
How much horsepower will a plenum spacer actually add?
Will a spacer work with my front strut bar?
Do I need any extra parts to install a plenum spacer?
How long does the installation take?
Will my car’s computer need time to adjust after install?
Is the cheaper plenum spacer a good buy?
What is the difference between the two Blox spacers?
Final Thoughts: The Verdict
If you want one dependable pick, the 350z plenum spacer winner is the Skunk2 Composite V2.0 because it pairs the thickest 5/8-inch design with the strongest claimed 10hp gain and an aerospace composite build. If you want the best owner-proven value and are fine upgrading the bolts, the Blox 5/8-inch is the one to reach for. And if a quick, slim, budget-friendly install matters more than peak gains, the Blox 5/16-inch gets you there without an engine bay overhaul.
How We Picked
We do not accept paid placement. Every pick is matched to a real buyer and a real use-case; we do not hands-on test units.
Sources & Methodology
Specifications: manufacturer listings and product documentation. Review insights: verified customer reviews, as of August 2026. Pricing: not shown on this page (it changes often); check the current price via the retailer link.
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