Since there has been some interest in my current intake, here is it broke down. I have tried numerous setups but this custom OEM+ version is the best and passes stupid SMOG visual check.
I also intensely studied the 2.5RS forums and looked at dyno charts showing that this IS the best when combined with a 2.25" cat back exhaust and equal length headers. Trust me!
This was a lot work as well as trial and error and willingness to start over again and redo it again several times. I think this was also the lightest combo if you trying to reduce weight.
One of a kind custom intake for the naturally aspirated Subaru EJ25D....
First up is you need the intake tract/duct and hoses from an earlier model Subaru Impreza or any Subaru that has this intake tube vs the stock version with the "torque box" behind the throttle body. Junkyard is your best buddy.
I had expensive high performance mandrel bent blah blah blah intakes which I constantly struggled with keeping the metal tubing cool (I used a laser temp gauge). This plastic is basically the same but rarely gets too hot to touch. So, actually a cold air intake if you keep reading.
Since the entire manifold needed to come out, I painted it wrinkle red and polished the runners and throttle inlet.
The reason I removed the manifold was to install stainless studs to make installing the 10mm thick teflon spacers and 2 sets of gaskets easier. Similar to 8mm Grimmspeed phenolic (previously installed) but thicker. This mod makes a big difference, the entire manifold now stays cool. No more engine block heat soak, only ambient engine bay heat.
"For every 5 degree reduction in temperature, increases power by 1%"
You have to extend the EGR tube and possibly grind your ignition coil pack mounts lower. Because the entire manifold assembly will be sitting ~12mm higher.
I was fortunate enough to work with the gasket maker. So he made 10mm teflon intake manifold spacers and a matching prototype 10mm throttle body spacer! Again 2 gaskets to ensure no leaks. Not sure if these were ever made available afterwards since I was the first car.
This spacer combo increased plenum volume as well as helped to keep heat transfer drastically reduced.
Using my custom ported, polished and knife edged throttle body that I did myself with the coolant hose permanently bypassed and the cruise control bits removed. Keep in mind you will need longer bolts if you use a spacer here. Definitely improved throttle response after just the throttle body swap.
I scored this GC8 v3 factory resonator/cold air intake inlet from the UK. It's what goes with those fender plugs. Grabs cold air from inside the fender behind the corner light up high, so no chance of sucking up water. FWIW, You really shouldn't just delete the "snorkus", seriously, it's just gonna mess up your MAF sensor.
I was also able to make the resonator from a SVX work in the 04 Outback with some persuasion. It too takes air from the same location but the box was hard to cram in the fender.
The intake tract will work with whatever air filter box but in order to use the EUDM WRX intake inlet/resonator you will need the matching filter housing box from an earlier model or have to drill a new mounting hole. You will need both halves!
BEST panel filter on the market IS made by Grimmspeed! Don't waste your money on any other filter! I also added a Filter Wears waterproof inlet cover/pre-filter to the resonator just incase of water spray. The factory option fender plug fills that hole.
And I'm not sure if this was an upgrade or not but here is the JDM JECS MAF I am also using. Used DEI gold heat reflective tape to keep it cool and extend the life. Possibly more consistent/accurate readings?
The only other things installed are a Weapon R catch can to the PVC, which DOES keep some crap out of the intake tract and off the throttle body but probably no real performance advantage. Plus a heat/flame resistant "sock", same as around my fluid reservoirs, over the bendy/flexible bit of the intake tract just after the MAF. That area is prone to splitting/cracking with heat and age!
Now for treasure at the end of the rainbow! I am actually gonna give you nerds the mother fucking part numbers! These can be life savers when searching for parts.
*You might have to make or reuse your PVC, crankcase, IAC valve hoses. So grab whatever is attached if your at the junkyard or hit up the auto parts store.
•Subaru PN's:
Intake duct/tract (EJ22): 14457AA111
Air filter housing/box: A53FA02 (upper) & A53FA01 (lower)
Fender resonator/snorkus (UK WRX): A21FA03 or A32FA01 or A21FA00
Fender plug: 46059FA000
•Grimmspeed PN's:
Dry-Con Air Filter: 060092
Intake manifold spacers (8mm phenolic): 015001















