Tatsu333's 2020 BRZ Sport Tech RS

[Compelica]

To add - got this info someplace else. Left is 1st gen, right is 2nd gen. Thanks @Jianlun

[Tatsu333]

OK - FA24 OEM headers and over pipe are on! I've reflashed my ECU back to 100% stock (I had been running some changes for cold start only with the ACE headers to try and quiet it down a bit), and went for a bit of a drive.

First impressions are as expected. It feels a bit more linear through the power band on full throttle pulls (I did 4 pulls from 2,000 rpm to redline - three in 3rd gear, and one in 2nd) with a *slight* soft spot just before 4,000 rpm, and it also pulls more strongly up top right to redline than I remember with the stock header. Driving some of my normal around-town roads, I don't notice any significant loss of low-end torque either. It pulls strongly away from stops / traffic lights / tight corners, even uphill from low revs. The sound is a little bit deeper toned in the mid-range than I remember with the stock FA20 header, but otherwise just as quiet (again, as expected).

Bear in mind that this is all still with the Billet Power Blocks installed, which shift the power curve down the rev range a bit, so someone else's experience with the FA24 headers on an FA20 might be a bit different. Also worth remembering that it's been four months since I had the stock headers on, so my recollection of how they felt and sounded may be hazy...LOL.

Vs. the ACE headers, I'd say it doesn't feel quite as strong in the midrange and maybe a *little* more restricted up top, but feels like it pulls away from stops and low revs more smoothly.

Anyway - overall, I'm happy with it so far.

I'm going to do a BUNCH of driving around under various conditions over the next week or so to give the ECU some time to make adjustments, and then I'll try to see about getting it on the same dyno as my previous pulls to see how it does on the stock tune.

EDIT: Darn - I just found out that the shop where I had done my previous dyno runs has closed down. So, no apples-to-apples comparison is possible, unfortunately.

[Tatsu333]

OK - on to the next project! Since I have five days where I don't have clients in my garage, I'm going to try and get everything outstanding done on my car.

Next up after the header swap is refinishing my MCA Traction Mod brackets.

With at best 16,000 kms on the car since they were installed in November 2021 and very little winter driving, I was a little shocked to see how badly rusted they were when the car was up on the lift back in May, so this has been on my mind for the last four months.

Here are some pics of them after removal:










...and here are a couple of pics after cleaning them up the best I could with solvent and a wire brush and then brake clean:






After letting them dry, I hit them with a coat of Tremclad Rust Reformer, and now they have to dry / cure for 24 hours before finishing:




I'll be finishing them with 2 or 3 coats of Tremclad Professional rust paint tomorrow, reinstalling, and then I'll probably spray some Kleen Flo Honey Goo around the assembly for a bit of extra protection.

While I'm waiting for the Rust Reformer to dry, on to my next project... (I'll update this post with further progress on this project tomorrow)

UPDATE 2025-09-28: Refinishing is done, and MCA Traction Mod brackets are reinstalled. The driver's side went in no problem, but for some reason the passenger side one was VERY difficult to get back in place. Took a lot of swearing and levering to get it to seat up in the stock bracket and align the holes, so of course my nice new finish got all scratched up.

Here's a couple pics of them before reinstalling:





Anyway, it's all back together, and I sprayed the whole assembly with Kleen Flo Honey Goo afterwards as a further layer of protection against corrosion. While I had the car up, I also increased the ride height all around to the maximum ride height supported by the RCE SS1's to give me a little more leeway with driveway ramps, etc. It's only 5-10 mm higher than before, but it's something!

[Tatsu333]

My next project today was to try the MAC Lifter Kit for fixing the bumper sag / gap / alignment issues. For context, I broke one of the loops (the one nearest the headlight) on the bumper side of the driver's side after hitting a driveway ramp a little too quick and smacking the bottom of the bumper on it.

Replacing the clips didn't help, and the regular metal repair plates from Etsy improved things a bit, but it still didn't fit quite right. Then I stumbled upon the MAC Lifter Kit.

The parts arrived from Australia just in time for this weekend, so I thought I'd give them a go. Since I already had the other repair plate installed on the bumper, I decided to just stick with that and only use the body side bracket from the MAC Lifter Kit.

While looking up the instructions for installing the kit, I came across this video, where the guy pretty much fixed the bumper gap by using a bolt and nut in place of the push pin at the top of the side marker bracket. I wish I'd seen this video before spending hundreds of dollars having two different repair kits shipped from Australia! Anyway - here's a link to the video:

So before installing the MAC Lifter Kit, I decided to just give this a try to see how it did. I removed the stock bumper bracket before doing this, and with just the bolt holding things in place, it actually looked OK:





That said, while the vertical gap was nice and tight, the bumper cover still didn't quite align flush with the fender. So, on to the MAC Lifter Kit!

The product page said that trimming of the headlight bracket would be needed for install, which I wasn't really keen on doing. Besides which, with the repair plate in place, that front loop was seating properly below the headlight / above the headlight bracket. Instead, I decided to cut the MAC Lifter Kit bracket short so that it would fit without cutting the headlight bracket:



That allowed it to fit just behind the headlight bracket when installed. I lined it up so that the smooth top edge of the lifter bracket was in line with the top of the headlight bracket, and maintained a consistent gap along the length of the bracket:





That got the bumper cover nice and flush with the fender line. I then installed the serrated flange bolt and nut (one of the stainless-steel M6x1.0 x 16mm sets that came with the MAC Lifter Kit - since I'm only installing the driver's side right now, I used one of the leftover sets) in place of the push pin at the top of the marker light bracket to secure things even more for a little extra insurance, and the fitment is PERFECT!!!





Since I had the side marker light out, I decided to finally get around to upgrading the side marker bulbs to LED's as well (they were the only bulbs not already switched over).

I'm going to keep the other MAC Lifter Kit pieces and previous repair plate for the passenger side for when I eventually need to fix that as well (right now it looks fine).

While my install wasn't typical / as recommended by the instructions, I'm happy to not have had to cut the headlight bracket for fitment. If you're looking to fix your bumper sag, gap or misalignment, I'd highly recommend the MAC Lifter Kit AND the trick of replacing the push pin at the top of the side marker light bracket with a bolt and nut.

Overall, I'd say this was a big win!

[Tatsu333]

I've had the cabin side of the sound tube blocked off with a 3/4" PEX plug since a week or two into owning the car, but just never bothered to remove the tubing, etc. in the engine bay. I figured while I'm waiting for paint to dry (literally) on my other project, might as well get 'er done!

I used the low cost DIY route, buying a 1-1/2" flexible pipe cap from Home Depot (for about $6 CAD including tax). It fit like a glove over the port on the intake tube.

[Tatsu333]

OK - with most of the little annoyances with my car sorted out and ZERO budget until I sell the ACE headers and other bits and pieces, I've started delving into self-tuning on ECUTek again. Available technologies have come a LONG way in the couple of years since I last dabbled on this side of things, most notably the availability of AI tools like ChatGPT, so I'm going to leverage them to hopefully make this easier.

I'm working on building out some project instruction files and prompts to make use of ChatGPT in analyzing my ECUTek logs and making tuning suggestions based on what is found in them. This was one of the most time-consuming parts of my previous self-tuning efforts, and while it's not instantaneous feedback by any stretch of the imagination, it's a LOT better than manually going through a 40 minute long, 53,000 line log file!

One big caveat here - ChatGPT WILL make mistakes and / or make stuff up if you don't constrain it with some very specific instructions or prompting.

For example, on one initial pass on MAF Scaling before building out the instructions, it was telling me to increase the g/s values for a section of the MAF Scaling table where LTFT's showed the ECU was consistently pulling fuel (which would indicate that the feedback from the O2 sensors was saying LESS air was coming in for a given MAF voltage than expected). So what was really needed was a LOWER g/s value (so that airflow was being correctly reported), not higher.

A VERY basic logic error that you'd think a "smart" AI wouldn't make, but it did.

So - short version: AI tools like ChatGPT have the potential to save a lot of grunt work when it comes to data analysis without purpose-built software, but don't trust them to necessarily provide you with the right answer. You need to build in some checks and balances with your instructions / prompting, AND spot check things to make sure it's on the right track!

Once I have things built out and tested, I'll be happy to share the project files for other people to try.

EDIT #1: And of course, now that I've decided to go this route, my laptop decides to die... Looks like one of the hard drives failed. Trying to repair it now, otherwise I have to spend money I don't have to get a new laptop. To be fair, I guess, it IS eight years old. Just annoying, and not in the budget at the moment.

EDIT #2: After many hours of fighting with it to try and get my laptop back up and working, I decided to just bite the bullet and picked up a new (to me) laptop instead. Now getting that set up, and then I'll be back on my way with self-tuning...

[Tatsu333]

I'm making really good progress with building out the instructions, etc. for ChatGPT to assist with self-tuning using EcuTek. So far I've dialed in the process for tackling MAF Scaling and instructions for evaluating performance improvements based on before / after logs.

I've also got some preliminary work done on the process for adjusting cam timing for NA mods like headers, BPB's, etc. based on before / after logged data. I'll be testing out the cam timing changes the next time I have free time on a good weather day to do back-to-back WOT pulls.

Once that's done, I'll move on to dialing in ignition timing next.