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Discussion Starter · #1 ·
Hello everyone,
I have a brand new 2021 STi which is my daily driver car. I'm looking into tuning it over time and I'm aware that tuning the car voids your factory warranty. Before I go Cobb Stage 1, I wanted to ask the community what mods are recommended to improve the reliability of the car to avoid possible failures as much as possible.

I'm about to get the IAG Air / Oil Separator for now.

Are there any other parts that I should consider as well?

Thanks!
 

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IAG AOS is deff a good one.
Cyl 4 cooling mod or equal length headers is another (the latter being a performance mod too, the former being way cheaper).
The Accessport will take care of the factory tune.
I recommend getting the front end wrapped in Xpel or similar.
Subaru's have thin paint and these cars get chipped up pretty easily.
At my mileage, my front end is in the kind of shape most cars are in at under 5k due to the wrap.

Otherwise, here is what I do for my sti:
A bit OCD, but at 80k miles it's stupid clean and any enthusiast would want it when I go to sell it.

1. Oil changes every 3k instead of 6k. I use Motul 5w40. This one is kind of a standard that enthusiasts follow for sti's, even if you aren't obsessive about the other things below. For oil, your call, but I'm pretty sure Motul and Rotella are generally the standard. I jumped up to the 40 series cause it's a bit better for a car that isn't stock, and my other car uses a 40 series, so it makes it easy to buy in bulk.

2. I always fuel up with better than 91 octane. Depending on where you live the 91 can be less than great, and that contributes to knock. You'll see what I mean when you get the Accessport and can monitor these things. I live in Canada so we have '94 octane', which I use exclusively. Find out about the quality of the gas in your area. 91 might be fine where you are, but it also might be meh. There is actually a special tune on the Accessport if you live in Arizona, California, or Nevada, because the 91 there is particularly bad, so Cobb has a 'safer' tune meant for these areas.

3. I keep every service, maintenance, or modification receipt in a large envelope in order.
I also have a 4 page word document with everything that was ever done to the car at what date and mileage.
Example (km's cause Canada):
Font Brand Darkness Composite material Circle

While this is totally unnecessary, when the previous owner broke this out when I went to meet to see the car, the thought of haggling on price vanished from my mind and I started thinking about how quickly I could put a deposit down.
I've also obviously maintained this practice, as I do a similar thing for my other car.
Only takes 5 mins to file the receipt into the envelope and add a line to the word document, and then if I ever run into warranty concerns later on a part or mod, I know where the receipt is and it's generally easy to find.

4. If you live where it snows and they salt the roads, get the car sprayed. I don't mean the black undercoating stuff (cause that's junk), I mean oil spray. I don't know what you have in the states but here we have "Krown" and I get my car sprayed every fall. While the spray can look a bit messy in the spring when it's in your door jams and engine bay, I don't have a spec of rust on the bottom of the car and I haven't encountered a single bolt that was even mildly difficult to remove. If you've never had this done before, good thing to read up on!

5. Did I say OCD? Oh ya... I start the car every morning and let the coolant get up to 100F before I leave my driveway. Takes less than 5 mins, even in the winter time. I also only ever do partial throttle until the car has been at operating temp for at least 5 mins. Seems extra AF but at 80k (130k km), my car doesn't burn a spec of oil.

Otherwise, don't floor it in 5th or 6th gear, or below 2,800rpm.
Always get the revs up by leaning into the throttle or downshifting before you mat it.

The 21' is the most refined sti (duh) so enjoy it!
Even if you don't live where it snows, don't pass up the chance for a road trip.
The sti is an absolute beast in the winter time, and puts pretty well everything else to shame except a handful of cars that can hang with it (RS3, R, RS, Evo, A45, etc.)

Oh, and welcome!
 

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Since this is your daily, you might want to look into the downsides of a AOS in colder climates. An AOS is one of those things that's become a commonly recommended mod but may not actually be necessary, or even beneficial, and may even be detrimental.

If you're dead set on it I'd go with a dual catch can setup instead. Radium makes a good one, Moroso has a couple options, and this company I recently came across called ADD W1 although I'm not sure if they offer a direct fit application for your STi.
 

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Since this is your daily, you might want to look into the downsides of a AOS in colder climates. An AOS is one of those things that's become a commonly recommended mod but may not actually be necessary, or even beneficial, and may even be detrimental.

If you're dead set on it I'd go with a dual catch can setup instead. Radium makes a good one, Moroso has a couple options, and this company I recently came across called ADD W1 although I'm not sure if they offer a direct fit application for your STi.
This right there!! AOS recommendation is like second nature here. Personally, im not on AOS bandwagon. If your arent seeing oil consumption or severe pooling in the manifold then it isnt needed. Oil in the intake track is pretty common on forced induction aplications. Now how much oil in there is a different discussion.

I think one of the best mods for these cars is ELH. It wasnt until i made the switch myself that i saw how much better the car drove and performed on a daily basis. Of course ELH would require a protune to really maximize its potential. Since you just got this car, im sure you're hesitant on losing that classic boxer rumble, but you wont miss it after a day or so.
 

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Discussion Starter · #5 ·
Hey guys, thanks so much for the information!

Austin, thanks for all the information. I'm planning on doing the oil change every 3k, so we are good here and I've been using only 91 octane gas. I live in Colorado and I'm not sure if we get a good 91 octanes here so I'll have to do some research. We do get a lot of snow in Colorado during the wintertime and I'll look into getting the car spray for rust. I am OCD as well and I've always kept receipts and everything that I did to my previous Ford Focus ST. When I sold it, I handed a USB drive to the buyer with all the documents of maintenance, etc. He was very thankful!

A5M and Jay, thanks for the clarification on the AOS. I'll do some digging and see what I can find. Also, what's an ELH?

Thanks, guys!!!!
 

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Hey guys, thanks so much for the information!

Austin, thanks for all the information. I'm planning on doing the oil change every 3k, so we are good here and I've been using only 91 octane gas. I live in Colorado and I'm not sure if we get a good 91 octanes here so I'll have to do some research. We do get a lot of snow in Colorado during the wintertime and I'll look into getting the car spray for rust. I am OCD as well and I've always kept receipts and everything that I did to my previous Ford Focus ST. When I sold it, I handed a USB drive to the buyer with all the documents of maintenance, etc. He was very thankful!

A5M and Jay, thanks for the clarification on the AOS. I'll do some digging and see what I can find. Also, what's an ELH?

Thanks, guys!!!!
ELH stands for Equal Length Header.
 

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Good tips here. There are stickies on this as well. If you have any questions there are knowledgeable people in here. A lot of the reliability will come from how you treat and maintain the car as well.
 

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Also, what's an ELH?
They say a picture is worth 1000 words.
Automotive exhaust Gas Auto part Bicycle part Metal

Stock above, Tomei below.
It's pretty well common knowledge by now that the Killer B header has some advantages to it's design, and uses a superior stainless steel, but I went with the Tomei to save a few bucks and paid to have it Cerakoted for rust protection.
You can technically install these without a tune, which is what I have done for now, but a pro tune maximizes their power potential, which I've already got booked for later this month!
I was Cobb Stage 2 before, then added the headers and a fuel pump, and even without a protune the torque is definitely noticeable.
I don't know how deep you plan to go on the sti, but if you ever intend to go a smidge past a basic Cobb stage 2 or get a pro tune done, add ELH to your list for sure!
 
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You can technically install these without a tune, which is what I have done for now, but a pro tune maximizes their power potential,
Just to add to this... We don't recommend anything beyond 'normal' driving. A well designed header will have a positive impact on VE and that can cause open loop lean conditions. The car will certainly feel faster, but a Pro-Tune is HIGHLY recommended as part of the upgrade recipe. Not only can it add additional power, but most importantly, longevity.

We get asked regularly, "can I drive the car after installing KBM headers?". Of course you can, but ideally, it's to the tuning session, or just keep your foot out of it until your appointment :)
 

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"Normal driving"... I have found I have to be specific with this. I'll send out tunes and their "normal driving" is basically getting on it. :p
 
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