I know the factory K&N replacement is E1009, and a few people have used E0773 successfully by also removing the factory "Neck", but both have their "disadvantages"....
Replacing the stock filter with E1009 does nothing to eliminate the factory necked-section and the in-airbox resonator. The necked section has an 80mm ID, but then opens up to the MAF ID of 85mm, followed then downstream with an "accordian" hose ID of ~90mm and the hard-plastic TB duct (and TB) of ID 90mm. The biggest restriction in this system is still the 80mm opening at the neck...BUT, the airbox remains "sealed" as best as possible with the blockoff flange extending from the bottom of the Neck, keeping the intake charge as cool as possible.
Replacing the filter with E0773 eliminates the factory Neck and the in-box Resonator, as the filter connects directly to the MAF-end. However, the airbox is no longer sealed due to the blockoff flange (molded on the Neck) also being removed. This opening will then allow more underhood heat to propogate into the intake airtract than the factory setup originally allowed. You will get more flow, but you may get more heat. In addition, its been said that the E0773 filter takes a bit of effort to get it to "fit" (deform) underneath the factory airbox lid.
Well, I removed the stock intake system today to have a bit of a look-see. There's a couple possibilities that I am looking into, but there's one pretty simple, cheap, and likely effective alternative to getting the extra flow while still using the factory Neck & OEM sealing capabilities:
1) Remove the airlid, and remove the in-airbox Resonator from the round 48mm OD "auxiliary" hose that extends from the Neck.
2) Remove the factory air filter.
3) Install E1009 to the factory Neck.
4) Install RU-1280 -or- RU-0400 to the 48mm OD hose. My quick calculations show that they will fit where that rectangular resonator once was.
5) Reinstall the factory airlid, using the factory Neck's flange as the seal, and enjoy the hopefully newfound power with your *two* (well, a fullsize and a midget) K&N filters installed.
What this setup enables is the inlet flow from the 80mm ID opening (factory air-filter), AND also inlet flow from the 43mm ID opening that once connected to the Resonator....while still completely sealing your airbox from sucking-in the engine heat. RU-1280 is about $30 from Jegs, so it could be a very CHEAP flow-enhancer, combined with the FREE mod of enlargening the headlight opening (call it the EHO mod).
My next step is to purchase the two filters, and then do some before-after flow testing with my homemade manometer.... Stay tuned....!
Also, for anyone doing a homebrew CAI w/ hoses & whatnot, be sure to USE some sort of accordian (or hump) hose for a section. The motor DOES torque-over upon heavy throttle, so you need to have an accordian section to accomodate this. Otherwise, I'd say you will run a pretty good risk of pulling-apart one of your clamp-joints, and/or splitting a section of ducting. Just a PSA.
Replacing the stock filter with E1009 does nothing to eliminate the factory necked-section and the in-airbox resonator. The necked section has an 80mm ID, but then opens up to the MAF ID of 85mm, followed then downstream with an "accordian" hose ID of ~90mm and the hard-plastic TB duct (and TB) of ID 90mm. The biggest restriction in this system is still the 80mm opening at the neck...BUT, the airbox remains "sealed" as best as possible with the blockoff flange extending from the bottom of the Neck, keeping the intake charge as cool as possible.
Replacing the filter with E0773 eliminates the factory Neck and the in-box Resonator, as the filter connects directly to the MAF-end. However, the airbox is no longer sealed due to the blockoff flange (molded on the Neck) also being removed. This opening will then allow more underhood heat to propogate into the intake airtract than the factory setup originally allowed. You will get more flow, but you may get more heat. In addition, its been said that the E0773 filter takes a bit of effort to get it to "fit" (deform) underneath the factory airbox lid.
Well, I removed the stock intake system today to have a bit of a look-see. There's a couple possibilities that I am looking into, but there's one pretty simple, cheap, and likely effective alternative to getting the extra flow while still using the factory Neck & OEM sealing capabilities:
1) Remove the airlid, and remove the in-airbox Resonator from the round 48mm OD "auxiliary" hose that extends from the Neck.
2) Remove the factory air filter.
3) Install E1009 to the factory Neck.
4) Install RU-1280 -or- RU-0400 to the 48mm OD hose. My quick calculations show that they will fit where that rectangular resonator once was.
5) Reinstall the factory airlid, using the factory Neck's flange as the seal, and enjoy the hopefully newfound power with your *two* (well, a fullsize and a midget) K&N filters installed.
What this setup enables is the inlet flow from the 80mm ID opening (factory air-filter), AND also inlet flow from the 43mm ID opening that once connected to the Resonator....while still completely sealing your airbox from sucking-in the engine heat. RU-1280 is about $30 from Jegs, so it could be a very CHEAP flow-enhancer, combined with the FREE mod of enlargening the headlight opening (call it the EHO mod).
My next step is to purchase the two filters, and then do some before-after flow testing with my homemade manometer.... Stay tuned....!
Also, for anyone doing a homebrew CAI w/ hoses & whatnot, be sure to USE some sort of accordian (or hump) hose for a section. The motor DOES torque-over upon heavy throttle, so you need to have an accordian section to accomodate this. Otherwise, I'd say you will run a pretty good risk of pulling-apart one of your clamp-joints, and/or splitting a section of ducting. Just a PSA.