I search this forum and did not find but a few DIY mounting options for mating the OEM box to the RB Ram Air Duct. (I even found one involving cutting a plastic bucket and rolling it into the proper shape-which works, but that just isn't my style.)

I went to Menards and purchased a 4" to 4" Plumbqwik rubber PVC connecter as pictured below. This item cost me like 6 bucks or so. The first thing you need to do is remove the metal clamps and then turn the hose inside out as pictured below:

 

Next, follow the Racing Beat instructions regarding the ram air install up to the point were you actually mount the duct behind the bumper support. At this point take the small end of the Plumbquick connector (see picture w/arrow) and feed it through open hole from the intake side. Once in place, the small end should be facing toward the front of the car, while the large feeds to the OE Box (see pics). The rib on the large end actually "locks" the piece into place and lines it up nicely with the opening:

 

Due to space limitations by the upper mounting tab sitting right above the duct, the small end will feed INSIDE the duct opening. This is actually a decent seal. If you so choose, you could add a small strip of foam around the opening to further tighten the seal, but IMHO it is not needed. I included a pick below to show the path form the OE Box to the Ram Air. It was very sunny that day and I could see no light coming in. Now the OE box will simply fit back into the large side. This is where I may remove the stock foam and add a slightly thicker section. As you can see, there is a small gap on the driver's side; however, upon running the car, I could not feel or hear any air leaking past it, but could definitely feel and here the intake hiss from ram air duct! I also need to mention that you will need to plug up the vacuum line that feeds the VFAD.

 

First impressions are great! The throttle response feels much improved and the port operations seem smoother. I am also running a gutted OE box with a K&N X-Stream Filter (The one with a built-in velocity stack), and only 1 MAF Screen. It pulls much better and the sound is stock until you lay it down! Considering I got this duct used, and the filter was 1/3 the cost of the REVi, I am very happy with the results and probably have 80 percent of the gains and 40 percent of the cost compared to the REVi+Duct combo!

 

Wait, I'm confused. I thought the ram air duct hooked up to the OEM air box without modification.

 

how does the 4" plumbquick mount up to the exit of the ram air duct when thats a 6"x4" oval?

 

It does not mount direstly to the oem box. There is about a 4 inch gap in the radiator core support.

Prober:
On that end it mounts inside the duct. The 4" duct is inside diameter-add material thickness of about 1/2" and the fact that the gap in the core support appears a little smaller than 4x6"s =>oval that fits perfectly inside the duct. As you can see from the pictures it all mounts in fairly well.

 

Do you have a part# for the K&N X-Stream Filter you used?

 

lol, modding a plastic bucket isn't your style but turning a rubber plumbqwik inside out for a duct is

----> just ing you

cutting off the factory horn and mounting a filter on it was pretty smart

 

I like to think so

BTW, you can even get the 4x4 Plumbquick OVER the RB ram air duct as seem below. This was my first choice, but that damn mounting tab is in the way!

 

I am not japanese!

 

I second that request.

 

Turning that plumb-quick inside out was harder than I thought. It fought back but I got the little bastard in the end!!

 

Reviving an old thread here. I finally got around to doing this on Friday. The DIY was extremely helpful, finding the Plumquick adapter and turning it inside out was harder than I expected. Overall it seems like a good solution, certainly better than the 4" gap without the adapter. However it doesn't mate to the stock airbox as well as I thought it would. The driver side inlet gap is more significant than I'd like. I think I'll go with some thick weatherstripping to create a decent seal.

My driving impression is good. I don't notice any sound difference with or without the VFAD /duct. I noticed a louder sound when I dropped in the K&N earlier this month. The engine IS idling smoother, which surprised me as I thought it would be the other way around. It also seems to run smoother through the entire power band but this could just as easily be the placebo effect. After two days of driving I've had no problems, but yesterday I had a VERY hard start. I have an 07 model with the latest flash and the car was warm. This concerned me a bit. We'll see what happens...