Installing parts outside of a calibration

I do NOT recommend installing ANY parts outside of a calibration.  Ever.  End of story.

The only benefit is "cost saving" by not purchasing another calibration.  A calibration is made for the specific mods and condition the vehicle was in during the calibration process.  When you are removing and reinstalling parts you can have install errors, induce a leak or any number of other issues.  There may have even been a small leak or some other minor issue during the initial calibration, which may get corrected during the install of new parts.  So there is a chance the car may run considerably different than it did before.

If you put the car back together and something is off, you are going to email your calibrator with questions and wanting him to look at logs, which he will charge for.  

The best practice is to gather all your parts, install them all at the same time and pay for a single calibration.  I know many people can't afford to buy everything all at once, but for most stock turbo mods anything you would have to buy would accrue minimal interest on a credit card compared to paying for multiple calibrations within a 12 month span.   The interest accrued over 12 months on a $3,000 balance at 30% is $418.  If you would pay $600 for a calibration, then $400 for another calibration 12 months later for added parts, the cost is $1,000.  If you put the extra parts on a credit card you would pay $600 + $418 over 12 months, virtually identical cost.  

• DATA!  Be proactive and be prepared.  
• Immediately before changing/adding a part, do a cruise log, 3rd gear log and a log of random boostage in various gears.  Save the logs as pre-mod_cruise, pre-mod_wot, pre-mod_random.   ** It is imperative that the pre-mod logs be done immediately before changing parts.  Logs from 6 months prior or even a week prior are basically meaningless.  **  
• Before doing the logs, put boost, DAM, FBKC, FLKC, AF Correction 1 and AF Learning 1 on the AP 6-gauge screen. 
• After each log, snap a pic of the AP screen with your phone so you have min/max values for boost, knock and fuel corrections.  These AP screenshots are for YOU to have an easy data reference.  The calibrator will just use the logs.  Name the screenshots pre-mod_cruise_SS, pre-mod_wot_SS, pre-mod_random_SS.     
• Once the mod install is complete, reset the ECU via the AP, then repeat the same logging and monitoring process you did pre-swap.  Cruise log, 3rd gear log and a log of random boostage in various gears.  Save the logs as post-mod_cruise, post-mod_wot, post-mod_random.
• Snap a pic of the AP screen after each log so you have min/max values for everything.  Name the screenshots post-mod_cruise_SS, post-mod_wot_SS, post-mod_random_SS.   
• Now you can simply put the corresponding AP screen shots side by side and compare the data.  If the post-mod boost levels, knock values and fuel corrections are all in line with the pre-mod levels, then you’re likely good to go.  
• If the post-mod data has overboosting, excessive knock, DAM drops and/or huge fueling corrections, then there may have been an install issue or tuning may be required.    
• If there is an issue and you need to pay a calibrator to help troubleshoot, you have the 3 pre-mod and 3 post-mod data logs already prepared to send.   

The effects of changing exhaust components can vary greatly depending on the complete modlist and which component(s) are changing, but these are the general concepts.

• Exhaust components change the diameter, length and shape of the piping that is both feeding the turbine wheel and causing back pressure on the turbine wheel.  The turbine wheel is what drives the compressor wheel and ultimately makes/regulates boost.  
• Remove small restriction = boost will stay the same
• Remove big restriction = boost will increase 1-2 psi
• Remove multiple restrictions = boost will increase 3-4 psi 
• Remove all restrictions (straight pipe) = boost will increase 4-6 psi
• Remove all restrictions (bumper exit) = boost will increase 6+ psi

Can exhaust components be run without any updates, yes.  Is there any guarantee that the boost and fuel trims will stay in check and no CELs will pop, no.   

Do I recommend installing exhaust components without an update, no.  

All of the differences between vehicles is the whole reason OTS maps don't work very well and that we calibrate the cars in the first place.

• Boring/honing the cylinders can lead to variance in engine displacement
• Decking the block and heads removes material and can lead to changes in compression ratio
• After market pistons and rods are different sizes, shapes and weights than OEM components and can lead to changes in rotating mass
• Changes in displacement, compression ratio and rotating mass all effect how the car needs to be calibrated.
• I would never advise anyone to run the same calibration, even if you're not changing any other part besides replacing the short block.  

The gear ratios in the ECU need to be updated via an updated map.

• Fixes gear display on dash to match STi gears
• Fixes gear position logging parameter to match STi gears
• Correct gear position reading allows all "per gear" compensation tables to work as intended.
• Whether or not additional mapping changes are needed is a hard question to answer.  I don't believe I've ever had to drastically change mapping after a swap.  But if the clutch on the WRX tranny was slipping at all the car may overboost with a newer clutch.  
• I charge $25 for updating the map. 

• Do I recommend installing an intake outside of a calibration?   No.
• Intakes are the main part that should absolutely never be installed without a calibration with the proper mass air flow (MAF) scale for the intake. 
• The MAF sensor in the intake pipe measures the airflow and provides fuel to the car based on the MAF scale in the ECU.  So in essence the intake controls the fueling over the whole powerband of the vehicle.  
• Every intake has a different MAF scale.  There is a plot of a 2015 WRX stock intake vs ETS intake vs CobbSF intake at the bottom of the page.  The % difference between the MAF scales will equate to the % difference in your AFR and/or AF Corrections.
• Running an intake on the stock MAF scale or another intakes MAF scale will not fuel the car correctly. 
• If you're going to stick with Cobb OTS maps, then just get the CobbSF intake.  
• When companies say "our intake doesn't require an updated calibration" they really mean "the fuel corrections/learning are within a range that we deem acceptable to run without any updates".  
• I've been in California for 20 years and before that I lived in AZ.  So I have always dealt with crappy 91 octane.  But most intake manufacturers live in states that have 92 or 93 octane.  So they don't really care about 91 or ensure that they thoroughly test it on 91 octane.  I bet you can check every intake maker's website and not a single one will have a dyno chart on 91 octane.  Then take into consideration places like Alaska that only has 90 octane, Canada which uses ethanol free 91 octane (aka 91e0) or Australia that uses 98e0 RON which has knock resistance comparable to 91e10 AKI (US).  
• Mishimoto actually took my advice and added a disclaimer on their intake "Mishimoto does not recommend using the intake with 91 octane fuel and no tune.  Using the intake with 91 octane and no tune may damage your engine."  Although it's basically hidden.  It's not on the main page with the intake features, you have to click on "Tech Specs" and then it's at the bottom of the page.  But C+ for effort.  
• The main issue is that 99% of aftermarket intakes are larger than the stock intake, this means that the air fuel ratio (AFR) across the whole powerband will lean out if you install it on a car running the stock intake MAF scale.  Anyone that has logged a stock vehicle on the stock file (stage0 on the AP) on 91 octane has seen that the cars already knock excessively and the DAM is almost always below 1.  
• Leaning out the AFR on a car that is already knocking will just make the car knock more.  Installing a part that will cause more knock is a horrible idea.  
• When Cobb carried OTS maps for other manufacturer intakes they had OTS maps for the ETS and Mishimoto intakes....and both say their intake doesn't need any calibration updates.  Cobb would not have wasted the time to make separate calibrations if it wasn't necessary.  

Running an intercooler without an updated calibration is mostly pointless.  Almost all the gains from an intercooler come from being able to safely run more boost, timing and a leaner AFR without knocking.  There are many different intercoolers with different cores, different pressure drops, different efficiencies, etc.  

Can an intercooler be run without an updated calibration, yes.  Is there any guarantee that the boost and fuel trims will stay in check, no.  

Do I recommend installing an intercooler without an update, no.  

The stock boost controller is a 2-port EBCS and operates at 10 hertz.

The aftermarket EBCS' are 3-port and operate at 30 hertz.  

The variation in the frequency between the two solenoids is the reason you get the flutter sound with an aftermarket EBCS.  The flutter can be lessened by adjusting the frequency.

Do I recommend installing an EBCS without an update, no.  

Can an AOS or CC's be installed without any updates, yes.  I have tested both the street and comp AOS' and neither changed the fueling or boost by a significant amount.  

BUT, like it says in the first paragraph on this page, installing any part opens yourself up to induce leaks or other issues.  If an AOS line is kinked, hooked up backwards, PCV hooked up backwards, PCV failed, etc..then these issues will not be easily visible by indications on the AP gauge screen.  

Do I recommend installing a AOS/CC's without an update, no.