2015+ WRX Recommended Parts

My advice:  Either run a Garrett TMIC w/ stock charge pipe or get a FMIC.  The best performing TMIC's are $1,000-$1,400 with charge pipes.  For that money you can get a PRL or Process West FMIC which have larger cores, will cool the intake manifold temps better and result in less knock.   Basically no TMIC below the Garrett is worth buying.  The Garrett is larger, cheaper and performs better.  And once you're considering spending $1,000-$1,400 on the baller TMIC's, the better move is to spend that money on a FMIC.  

Best bang for your buck TMIC:    

• Garrett TMIC - $565 - $640

Best Performing TMIC's:  

• Cobb TMIC - $1,020 w/ charge pipe (charge pipe is required)
• Process West Verticooler -$ 945 (charge pipe included)
• Grimmspeed TMIC - $1294 w/ charge pipe
• Mishimoto Race - $1,441 w/ charge pipe 

TMIC's NOT WORTH BUYING

• TurboXS, AVO, Mishimoto Street, PW KhanaCooler, NP Boosted, Rev9

Best bang for your buck 

-  Process West FMIC

• Core = 980 in^3  
• Price = $1,262 
• Located in Australia, which can make communication and warranty claims more difficult.  

Biggest FMIC's available   

-  GrimmSpeed FMIC

• 4" Core = 1,188 in^3  
• Price = $1,560 - $1,880  

-  ETS FMIC

• 4" Core = 1,182 in^3  
• Price = $1,754 - $2,704  

-  AMS FMIC 

• 4" Core = 1,169 in^3  
• Price = $1,164 - $1,552  
• ** WARNING:  Requires cutting the plastic under tray & fender liner on the passenger side directly below the intake.  This allows water easier access to MAF extension harnesses and filter, which can lead to corrosion in the connectors, which can lead to dangerous fueling issues, extension harness failure or MAF sensor failure.  I would not recommend this FMIC if you live where it excessively rains or snows.  **

-  Cobb FMIC

•  4" Core = 1,056 in^3  
• Price = $2,025
• CARB Approved

FMIC's NOT WORTH BUYING 

-  Perrin FMIC

• 3.5" Core = 907 in^3  
• Price = $2,065   
• Small core & expensive.  Better options available for the money.

-  Mishimoto FMIC

• 3.5" Core = 789 in^3  
• Price = $1,262 
• Small core & expensive.  Better options available for the money.

For FMIC's that do not retain the stock o-ring at the turbo outlet, I recommend using this gasket instead of the provided paper gaskets.  The paper gaskets almost ALWAYS LEAK unless the pipes are perfectly aligned and seated perfectly.  If the link is broken it is Mr. Gasket #738G    https://www.jegs.com/i/Mr-Gasket/720/738G/10002/-1  

EBCS will produce a smoother boost curve and hold boost better in the midrange, thus picking up hp/tq through having a better and more consistent boost curve.  Should be considered a required mod...especially with a catless exhaust system.  Can I run an EBCS without a tune, yes if you stay out of boost.  Best to coordinate with your tuner and have a map ready to load before you even begin the install.  Always best to have your tuner check logs post install to make sure you didn't induce a leak or cause a problem during the install.

GS and Cobb EBCS are preferred.

Perrin EBCS installs in conjunction with the stock BCS.  More vacuum lines and different mapping than the GS and Cobb units.  GS and Cobb provide a cleaner install and make my life easier since the mapping is the same.

Company23 anti surge EBCS is not necessary.

The purpose of changing an intake on a MAF based car is to stop from maxing out the MAF voltage.  This is accomplished by making the piping larger that houses the MAF sensor.  So basically the MAF sensor is moved out of the airflow.  As a result most aftermarket intakes will have higher AF Correction and Learning since the sensor is actually in less of the flow.  Almost all of the intakes utilize a MAF extension cable which seem to be prone to getting moisture into them which causes erratic fueling.  

I prefer the Grimmspeed Intake because it has a stopper on the MAF sensor flange to butt the filter up against.  So everyone installs the filter in the same spot.  All other intakes have "floating" filters, meaning that each customer can install the filter in a different spot on the intake pipe....this causes fueling issues and makes troubleshooting more difficult (and by more difficult I mean nearly impossible).  On other intakes moving the placement of the filter by just a 1/4 inch can change the fueling by 20-30%, which makes troubleshooting very difficult.  

Intakes without boxes will make you lose power.  Full write-up here  https://phatbottituning.com/intakes-without-boxes 

An intake would be one of the last mods I would buy.  The hp gains are minimal on 91 octane, the increase in fueling corrections and possibility of MAF extension cable issues all outweigh the minimal gains IN MY OPINION.  Do they add power, yes.  Do they smooth out power delivery, yes.  I just simply recommend other parts first.  If increasing turbo and bypass valve noises are your goal, then I would recommend getting an intake over a bypass valve or a blow off valve.

I would personally put the money towards a good intercooler or flex fuel before buying an intake.  If you already have all those parts, then yes an intake will add power and smooth out certain parts of the power band.

Can I run an intake without a tune?   I WOULD NEVER RUN AN INTAKE WITHOUT A TUNE.

Despite Boomba's bubble video, the stock bpv works perfectly fine.  The stock bpv has a pressure relief hole in it.  It is designed to leak on purpose.  HOWEVER, stock ones need to be upgraded when dealing with larger than stock turbos.  It should be considered a requirement to have a BPV with an aftermarket turbo.  It is simply not a common issue for the stock bpv's to fail with stock turbos.  The stock bpv has been very reliable on stock turbo setups.  But if you must get one I would suggest the Cobb Version 2 BPV.  A BPV would be one of the last mods I would buy.  I would put the money towards an intercooler or AOS before buying a BPV.  

Can I run a BPV without a tune, yes.  The BPV will only make a difference if your stock BPV was leaking really bad.   Always best to have your tuner check logs post install to make sure you didn't induce a leak or cause a problem during the install.  There is no specific tuning for a BPV or a BOV.  The only time a real issue can occur when swapping a BPV/BOV is if your car was previously tuned with a leaking valve and your tune has the wastegate duty cycle increased to compensate for the leaking valve.  If you put a valve on that doesn't leak then your car will overboost.  The problem with detecting bypass valve leaks is that they are part of a closed system, so if they leak boost they simply leak it back to the intake tract so it's really not detectable in the log because it won't change the fueling.  As you see from Boomba's bubble video the stock unit already leaks, but it's so minor it doesn't play a role in any power loss and it's designed that way.  A blow off valve leak on the other hand will alter the air fuel ratio and is easily seen in a log.

A blow off valve should never be used on a Mass Air Flow fueled vehicle.  

A blow off valve simply decreases the performance of the vehicle.  The purpose of a bypass valve is to bypass the pressurized air when the throttle closes back to in front of the turbo to help keep the compressor wheel spinning during shifts.  

A blow off valve is taking this feature away.  So the turbo will spin down more when shifting.  The other major downside to a blow off valve on a MAF based car is that it's releasing air that was measured by the MAF sensor...so when that air is released, it makes the car run rich because the ECU is still injecting fuel for air that's no longer there.  This will prematurely foul the plugs and make your gas mileage go down because you're just wasting fuel every time you let off the throttle.   When the air is released you will notice your AF Correction and/or AF Learning go to very high negative values to try and compensate for the car running extremely rich.  If the rich condition happens at or near idle it can cause the car to sputter and or stall.  This can NOT be tuned out most of the time.  The solution is to pre-load the BOV more by tightening the allen bolt on top of the BOV, using a higher pressure spring in the BOV, or by adding washers below the springs to increase the preload.  If the BOV is not adjustable, then remove it and light it on fire and put the stock BPV back on the car.  

An upgraded bypass valve should be considered a requirement when upgrading the turbo.  The stock unit can't handle higher boost pressures and may begin to leak.

ACT Heavy Duty Street - Part#  SB11-HDSS

• Price = $995
• ACT's CRANK Torque Rating = 410 lb-ft 
• Equivalent WHEEL Torque Rating = 330-350 lb-ft
• This clutch should only be used for stock turbo pump gas setups that have no plans to upgrade to flex fuel or bigger turbos.
• Flex fuel, built engine and bigger turbo setups will surpass the torque rating of this clutch. 

ACT Extreme Street - Part#  SB11-XTSS

• Price = $1,050 
• ACT's CRANK Torque Rating = 510 lb-ft
• Equivalent WHEEL Torque Rating = 385 - 405 lb-ft
• Can be used for daily stock turbo flex fuel setups. 
• Built engine setups, SEND IT toons and bigger turbo setups will likely be beyond the torque rating of this clutch and should use the Clutch Masters 725 Series Twin Disc.

• I would personally spend money elsewhere before buying headers.  
• None one of the aftermarket headers utilize heat shielding.
• Swaintech coating is an extra $400 and 8 week wait time.  And then you're in $1,200 for headers.  You could have bought a SoCal v3/v4 or an FP Blue and made way more power than a header will add.
• Wrapping headers creates a fire hazard and can also promote cracking.
• Increased oil temperature, no heat shielding and the header wraps around the oil pan. 
• Increased engine bay temperature, no heat shielding. 
• Fitment issues + flanges that aren't flat = header to block gasket leaks
• Never buy a header that utilizes slip joints.  Slip joints = guaranteed leak, it's just a matter of time.
• Un-equal length headers - not recommended.

Racing on 91 octane, or any pump gas in general, is just asking for trouble.  I highly recommend getting a flex fuel or race gas tune for track days, canyon runs or any type of hard abuse.  If you can't afford that then add in 4-5 gallons of 100 oct unleaded and fill the rest up with 91.  If you don't have 100 oct available you can also put in 3 gallons of e85 and fill the rest of the tank with 91.  Both the e85 and 100 oct  will add knock protection and make the car much safer.  You should always race on a full tank of gas to avoid fuel starvation.  There is a reason it's called RACE gas.

Even regular pump gas is not created equal.  While most stations across the US have 10% ethanol in the pump gas, lots of stations still use ethanol free gas (e0).  Ethanol free gas is worse than e10 gas.  The ethanol adds knock protection and allows the cars to make more power.  You can check which gas stations in your city/state carry e0 on this website  https://www.pure-gas.org/index.jsp?stateprov=CA  so you can stay away from them.

http://newsroom.aaa.com/2016/07/aaa-not-gasoline-created-equal/