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Hondata Reflash: 2002-2004 RSX Base: 5-Speed Manual-A1
Hondata Reflash: 2002-2004 RSX Base: 5-Speed Manual-A2
Hondata Reflash: 2002-2004 RSX Base: 5-Speed Manual-A3
Hondata Reflash: 2002-2004 RSX Base: 5-Speed Manual-A4
Hondata Reflash: 2002-2004 RSX Base: 5-Speed Manual-A5

Hondata Reflash: 2002-2004 RSX Base: 5-Speed Manual

Part Number: K20A3-M

5 out of 55 out of 55 out of 55 out of 55 out of 5 6 customer reviews

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The K20A3-M program advances the ignition, alters the cam timing and optimizes the fuel for a cold air intake headers and exhaust, adding 5-10 ft lb across the rev range.

This program was tuned specifically for a cold air intake, as they give the best power gains. Long cold air intakes work the best. The long cold air intake we tested with added 5-6 ft lb across the rev range from 2800 rpm up. By comparison the CAI makes more top end power from about 5500 rpm and up Hondata program makes significantly more torque under 5500 rpm. This graph shows only the CAI with no Hondata program.

This reflash is not suitable with nitrous due to the aggressive ignition advance.


You are responsible for paying for and sending your ECU to Hondata. You can send your ECU as fast as you would like and shipping costs normally start at $10.00 for ground and $60.00+ for next day air. We recommend using an express service (2 day or next day) through FedEx or UPS because they have the least amount of delivery problems, provide proper insurance, and have good package tracking. We recommend that you do not use USPS because of delivery issues. You are not sending your ECU to K Series Parts you will be sending it to Hondata directly and we provide all of the instructions on where it needs to be sent once your order is approved.


After we approve your order we will send you two emails, one email will be a Hondata form and the other email will be instructions for shipping and what items need to be included. Orders submitted by 3:00pm Mountain Standard Time Monday to Friday are normally approved same day. Orders places after 3:00pm MST or on Saturday and Sunday are processed the next business day.

Hondata normally reflashes ECU's the same day they receive them but they do get busy and it might take an extra business day. We recommend that you plan on a 3 day total turnaround time from the day that Hondata receives your ECU.

Return Shipping

Hondata uses K Series Parts FedEx account to next day air the ECU back to you once the reflash has been installed. This means that you do not have to pay for return shipping. Your ECU will arrive by 3:00pm the day after Hondata completes the reflash installation. Hondata does not provide us with a tracking number or notification when they ship the ECU back to you.

ECU Serial Number

The serial number is located on the ECU. Hondata has provided instructions on how to remove the ECU.

International Customers

K Series Parts cannot sell reflashes to customers outside of the United States per Hondata request. The shipping address must be a US based address.


Any 2002 to 2004 Acura RSX with manual transmission and ECU part number: PND A01 through A09


  • 5-10 HP increase across most of the rev range.
  • 10-12 ft/lb torque increase under 5000 rpm
  • Rev limiter optionally raised to 7300 RPM
  • No measurable difference in emissions from stock.
  • Fully dealer compatible - works with all Honda scan tools and equipment.
  • More torque than a stock K20A2 Type S under 6300 rpm. (see graphs above)


Any increase in RPM limit is at your own risk. If you suffer engine damage that is related to excessive revs Honda / Acura will not cover your warranty.

With regard to aftermarket parts, the law is that warranty coverage cannot be denied simply because such parts are present on the vehicle, or have been used. For more details read the K series FAQ.


Honda may not cover mechanical damage to the engine under warranty resulting from exceeding the factory red line. Hondata & K Series Parts will not cover any damage as a result of installing this product.


Brand: Hondata
Part Number: K20A3-M
CARB Approved: No

Customer Reviews

5.0 out of 5.0 5 out of 55 out of 55 out of 55 out of 55 out of 5

6 Total Reviews

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Most Recent

5.0 out of 5.0 5 out of 55 out of 55 out of 55 out of 55 out of 5

Best bang for the buck

By Johnny Gutierrez on 2/19/2018

I like the street drivability of the base model Rsx. This reflash definitely improves that drivability of the base even further. I would recommend the increased rev limit to benefit the that laggy 2nd to 3rd upshift. This is by far the best upgrade you can do for the base RSX.

5.0 out of 5.0 5 out of 55 out of 55 out of 55 out of 55 out of 5

Holy crap it works!

By Christian Polanco on 6/18/2014

So here is my review, Holy crap it works. So I went through Kseries online. They emailed me the instructions and they were very helpful. I shipped the ECU and the immobilizer on a Monday and it came back Thursday noon. I went through USPS next day shipping. Not bad for going from Maryland to California and back. So when it came back I plugged it in, let it idle for 10 minutes and drove it around. It actually moves now. The main difference for me is shifting from stand still. I really dont feel like Im going to stall now. Just give it slight gas and it just moves, no more shudder. The next thing is chirping. Now my tires are in good condition. When Im gunning it, it chirps 2nd every single time. I was surprised to have it chirp a little from 2nd to 3rd, but then again I was borderline redlining. But as far as rough torque, it hasn't changed. The behavior of the torque actually feels like it has a pair of balls now. I had to wait and wait for it to speed up in. Now the power delivery is just smooth and doesn't lag like before. It use to take me forever to go from 50-100. I would have had to really be pushing it hard and for a long time. With the reflash, that needle just moves. I glanced at my speedo when I was pushing it, and I said, "Holy shit IM doing 100 already???" I was still on 4th gear doing 5-6K rpms. I disconnected the battery for 5 minutes, reconnected and had it idle for 10 minutes and took it out for another drive but to be honest I really didn't notice much difference from the first drive. Like people said before, it changes the driving dynamics. Whatever hondata did, it feels like they spread the power throughout the power band. So the K20A3's power is transferred in a more usable power-band starting at 3K RPM. Unlike before the flash where all the actual power was in 5K and up range. We all know to get to 5K you'll either have to punish your clutch by downshifting to 3rd or just wait until you get there; which by that time the other car is already out of there. So in conclusion, before I couldn't feel myself get pushed back against my seat when I was gunning it. But now I can. Mods at the time: AEM SRI, Apexi N1 Muffler.

5.0 out of 5.0 5 out of 55 out of 55 out of 55 out of 55 out of 5

Tottaly worth the money

By Mrh239 on 1/27/2012

this is the easiest and probably the cheapest you can get for your base RSX that will make a significant difference in engine power and overall car driveability. Before the upgrade you get virtually no power under 3000 rpms with the AC on. Now the car has improved torque at any rpms. If all you need is a little more power for your RSX and this is the car you drive every day, get the reflash and you will be very happy!

5.0 out of 5.0 5 out of 55 out of 55 out of 55 out of 55 out of 5


By Rex Hamilton on 5/17/2010

I sent my ecu off on thursday got it back monday, and i can say its worth every penny! my 04 rsx will get up and go now!

5.0 out of 5.0 5 out of 55 out of 55 out of 55 out of 55 out of 5


By Josh G. on 2/4/2010

I was a little hesitant to purchase the reflash at first since I own a base model. the install was super easy, as I went to a shop just a few miles from hondata physical location. you can feel the difference in power and torque! I also have the greddy EVO II exhaust and AEM V2 intake, along with the reflash and royal purple oil, my base now puts down 200BHP(up from the stock 160) and somewhere around 170-172WHP, with much more torque than a stock K20A2 (I totally broke off a stock typeS on the freeway). the optional raising of the rev-limiter really helps to stay inside the power-band, and tho advertised to raise to 7300, mine will strech all the way to 7600 before it bounces off. I also purchased the gates racing serpentine belt, as my serp belt slipped off the pulley due to the extra RPM of the reflash causing my tensioner to need replacing, although I did have 119,000 at time of install. all in all, definitely worth it, as long as you have intake and exhaust to back it up!

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