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 of your modifications/car 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 modifications 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 (If on ecutek and uploaded via Phoneflash, put these into the datalog notes/comment section).   ** 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.  ** 
• Once the mod install is complete, reset the ECU adaptations via the EcuTek Ecu Connect App, 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 (If on ecutek and uploaded via Phoneflash, put these into the datalog notes/comment section)).
• Now you can simply put the corresponding datalogs side by side and compare the data (if you want to do this yourself). 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, 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 mod list 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 (Dumping right off the turbo) = 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.  

• 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 (SD vehicles are exempt). 
• 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. 
• Running an intake on the stock MAF scale or another intakes MAF scale will not fuel the car correctly. 
• 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".  
• 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.  
• 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.    

For BMW's, running an E50 stock turbo map with all the boost in hotter climate areas and no cooling mods is a big no no. Keeping safety limits on and your IAT hitting 165F + it will instantly drop boost and torque request limits to keep everything safe (this is for you guys out there wanting all the power and not doing one single cooling mod. Almost all the gains from an having cooling mods come from being able to safely run more boost, timing and a leaner AFR without knocking. There are many different manifolds with different cores, different pressure drops, different efficiencies, etc. but anything is better than nothing when it comes to cooling.

Can an intake manifold, heat exchanger, etc 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, intake manifold etc without an update, no.