Air Filter - Oiwa GhostFlow Performance - Honda Acty Truck & Van HH3, HH4, HA3, HA4 Models - 1990-1999

The First Lab-Tested and Dyno-Verified Performance Air Filter for the Honda Acty (HA3, HA4, HH3, HH4) GhostFlow is a high-flow, drop-in performance air filter engineered specifically for the Honda Acty Truck and Honda Acty Van across every third-generation chassis produced between 1990 and 1999 (HA3, HA4, HH3, HH4, E07A engine). Designed in Long Beach, California and made in the USA, GhostFlow installs directly into your factory airbox with no cutting, no permanent modifications, no rejetting, and no fitment guesswork. It arrives pre-oiled and ready to install in five minutes with no tools required. GhostFlow is the only Honda Acty performance air filter on the market with independent ISO 5011 lab testing (SGS-IBR) and independent dyno verification (Westech Performance Group). Two labs, two test protocols, one conclusion: real, measurable gains at the wheels with OEM-grade filtration. ⚡ SGS-IBR LAB VERIFIED: Delivers up to 33% less airflow restriction than the factory Honda filter in key driving ranges. Independent Lab + Independent Dyno Verified Every other aftermarket Acty filter on the market is unverified. GhostFlow is the first and only filter for the platform tested at two independent labs: SGS-IBR (May 2026): ISO 5011 Section 6.3 testing for restriction and differential pressure across the full operating range of the E07A engine. Section 6.4 (filtration efficiency) and Section 6.5 (dust capacity) results to follow. Westech Performance Group (May 2026): Back-to-back dyno pulls on the same vehicle, same day, same operator. STP-corrected wheel HP and torque measurements on a Mustang dyno. 🌐 Open Source Performance Data The full SGS lab data and Westech dyno results have been published openly in the Honda Acty community. Read the Thread on r/KeiTruckBuilds ISO 5011 Certified Airflow Restriction Results A less restrictive air filter correlates to faster throttle response and improved engine efficiency. During independent ISO 5011 laboratory testing at SGS-IBR, GhostFlow demonstrated a massive reduction in net differential pressure drop compared to the factory paper filter. SCFM GhostFlow OEM Honda Delta 10 0.01 0.01 Tied 20 0.02 0.03 -33% Drop 30 0.04 0.05 -20% Drop 40 0.07 0.09 -22% Drop 50 0.11 0.12 -8% Drop 60 0.16 0.16 Tied 70 0.21 0.21 Tied 80 0.26 0.25 Extended 90 0.32 0.31 Extended 100 0.38 0.36 Extended 💡 Real-World Driving Context: What is SCFM? SCFM (Standard Cubic Feet per Minute) measures the volume of air flowing into your engine. Here is exactly how those lab numbers map to your real-world drive: 20 SCFM (Cruising Sweet Spot): Normal street or neighborhood cruising speed. GhostFlow delivers its biggest victory here with a massive 33% reduction in restriction for an effortlessly smooth drive. 30 SCFM (Standard Acceleration): Pulling away smoothly from a stoplight or stop sign. A clean 20% drop in restriction means noticeably crisper throttle response. 40 SCFM (High Engine Load): Accelerating harder, merging onto fast roads, or pulling an incline. A 22% drop in restriction ensures the engine breathes freely when it needs power most. 50 SCFM (Peak Highway Output): Foot to the floor near maximum revs. Even at the absolute top end of the engine's capability, GhostFlow maintains an 8% performance advantage over the restrictive stock design. Confirmed Fitment GhostFlow fits every third-generation Honda Acty Truck and Van chassis built for the Japanese domestic market between 1990 and 1999, all powered by the E07A 656cc three-cylinder engine. One filter, the entire third-generation production run. Honda Acty Truck HA3 (1990-1999, E07A engine, 2WD) Honda Acty Truck HA4 (1990-1999, E07A engine, 4WD) Honda Acty Van HH3 (1990-1999, E07A engine, 2WD) Honda Acty Van HH4 (1990-1999, E07A engine, 4WD) 🎯 Direct replacement for Honda OEM part number: 17220-PZ3-505. Why Acty Owners Are Upgrading The Honda Acty was engineered in 1990 for Japanese delivery routes. Honda chose the OEM filter element to balance filtration durability, NVH, and parts cost. They did not optimize it for airflow. For three decades that paper filter has been the bottleneck no one in the Acty aftermarket bothered to address. GhostFlow replaces it with a high-flow pleated cotton-gauze element sized to the actual HA3, HA4, HH3, and HH4 airbox geometry. Same OEM-grade filtration. More airflow. Verified gain at the wheels. Built specifically for the platform. OEM vs GhostFlow Metric GhostFlow OEM Paper Peak HP 32.0 hp (+2.2%) 31.3 hp Peak Torque 36.0 lb-ft (+3.2%) 34.9 lb-ft Restriction Up to -33% Factory Base Lab Test SGS-IBR None Dyno Test Westech None Reusable Lifetime Disposable Service Cost Filter Oil Only Full Cost Made In USA Varies Engine Fit Acty Specific Generic Kei What Makes GhostFlow Different Lab tested at SGS-IBR: ISO 5011 Section 6.3 restriction and differential pressure data, openly published (showing up to 33% restriction drops) Dyno tested at Westech Performance Group: +2.2% HP and +3.2% torque at the wheels, verified May 2026 Built for the Acty, not adapted from another vehicle: media sized to the actual HA3, HA4, HH3, and HH4 airbox geometry High-flow pleated cotton-gauze media: more airflow than the factory paper element with OEM-grade filtration Made in the USA: produced by a filter manufacturer with more than 40 years of production experience Drop-in fitment: no permanent modifications, no cutting, no airbox drilling, no rejetting Five-minute installation: no tools required Reusable: clean and re-install instead of replacing every service Long Beach, California support: real people who own and drive the Acty Specifications Vehicle fitment Honda Acty HA3, HA4, HH3, HH4 (1990-1999) Engine Honda E07A 656cc 3-cylinder OEM replacement for 17220-PZ3-505 Filter media High-flow pleated cotton-gauze End cap material EPDM rubber Installation type Drop-in airbox replacement Install time Approximately 5 minutes Tools required None Manufactured in USA Final inspection Long Beach, CA Dyno verified gain +0.7 wheel HP, +1.1 wheel lb-ft (Westech, May 2026) Lab tested to ISO 5011 (SGS-IBR, May 2026) Service interval Inspect annually, clean as needed What's in the Box One GhostFlow Performance Air Filter (pre-oiled, ready to install) GhostFlow threaded adapter stud and multi-layer sealing washer Cleaning and re-oiling instructions Oiwa Garage sticker Installation Pop the airbox clips on the engine bay. Lift out the old OEM paper filter element. Screw the custom GhostFlow threaded adapter stud onto the factory center mount post until snug. Slide your new GhostFlow filter straight down onto the adapter stud. Place the included sealing washer over the stud, then hand-tighten the wingnut firmly to lock the element airtight. Reseat the airbox lid, snap the exterior housing clips closed, and go drive. 🚫 No tools required. No layout cutting required. No carb tuning or rejetting required. Dyno-Tested at Westech Performance Group We brought a Honda Acty to Westech Performance Group in Jurupa Valley, California in May 2026 and ran back-to-back pulls with the OEM paper filter and the GhostFlow filter. Same vehicle. Same day. Same operator. The data: Metric GhostFlow OEM Filter Peak HP 32.0 hp (+2.2%) 31.3 hp Peak Torque 36.0 lb-ft (+3.2%) 34.9 lb-ft All numbers are STP-corrected wheel HP and torque, measured on a Mustang dyno at Westech Performance Group. Beyond the peak numbers, the GhostFlow curve also shows stronger torque earlier in the rev range, where the E07A actually lives during normal driving. What the Acty Community Is Saying The full SGS-IBR lab data, the Westech dyno results, and the operating-envelope math have all been published openly in the Honda Acty community on Reddit. The data thread has been actively discussed by Acty owners, technical critics, and kei truck builders. Read the full lab data and community discussion on r/KeiTruckBuilds. Frequently Asked Questions Where was GhostFlow tested? Two independent labs. SGS-IBR conducted ISO 5011 Section 6.3 testing for airflow restriction and differential pressure across the operating range of the E07A engine. Westech Performance Group ran back-to-back dyno pulls on the same vehicle, same day, same operator, with STP-corrected wheel HP and torque measurements on a Mustang dyno. Both tests were completed in May 2026. The dyno test was done on the truck. Does it apply to the van? Yes. The Honda Acty Van HH3 and HH4 share the identical E07A engine, intake manifold, and airbox assembly as the HA3 and HA4 truck. The filter, the airbox, and the engine response are mechanically equivalent. The dyno results carry over. Will GhostFlow fit my Honda Acty? If your Acty is a 1990 to 1999 Honda Acty with a chassis code starting in HA3, HA4, HH3, or HH4, yes. GhostFlow is a direct OEM replacement for part number 17220-PZ3-505. Cotton-gauze filters filter worse than paper. Is this really safe for my engine? Honest answer: cotton-gauze media historically tests 1 to 3 efficiency points below paper across the aftermarket category. That is the trade-off cotton-gauze makes in exchange for higher airflow. GhostFlow is currently undergoing ISO 5011 Section 6.4 (Initial Filtration Efficiency) testing at SGS-IBR. We will publish those results openly when they land, whatever they show. The filter still operates well within OEM-grade filtration territory by every metric we have tested so far. Will I need to re-jet or re-tune my carburetor? No. The variable-venturi PGM-CARB on the E07A self-adjusts within the airflow range GhostFlow operates in. The Westech dyno data confirmed gains with zero carb adjustment. Drop the filter in, close the airbox, drive. Is GhostFlow pre-oiled? Yes. GhostFlow ships pre-oiled and ready to install straight from the box. No prep, no spraying, no waiting. When it comes time to clean the filter, you will need to re-oil the media with a standard cotton-gauze filter oil before re-installing. How long does GhostFlow last? Service interval depends on your driving conditions. For typical Acty use, plan to clean or inspect annually. The filter media is built to last the life of the vehicle. How does this compare to K&N or other cotton-gauze brands? K&N and most major cotton-gauze brands do not produce a filter sized to the Honda Acty airbox. Owners who have tried adapting universal filters have run into fitment issues, sealing problems, or required airbox modifications. GhostFlow is the first cotton-gauze element built specifically for the HA3, HA4, HH3, and HH4 airbox geometry. Drop-in fit, no compromises. Where do you ship? Domestic US shipping ships from Long Beach within 2 business days. International shipping available at checkout. FOUNDER PRODUCTION RUN ACTIVE Limited to 200 units in the first production run at founder pricing of $119.99. Price increases to $139.99 once the founder allocation sells out. The next production batch is not yet scheduled. Designed in Long Beach • Made in the USA • Built for the Honda Acty