We've been doing the "Gotts" mod on the 04+ since they came out and have had no adverse effects whatsoever. AFR is not significantly affected.

Mark, I think the holes in the resonators act a bit like "shock absorbers" to dampen out the "springyness" of the air inside. It's possibly like the tuned port in a base reflex speaker enclosure.

As far as the 6 holes in the bottom of the intake, these don't make sense to me at all. We used to see a flapper door in the intake that would pull air off the exhaust manifold during cold weather to aid in cold weather starting and running, but it would close when the engine got warm. These things are always open though. You could be right about them allowing additional air in during WOT at high RPM, but it seems like an odd way to do it. Actually, the Bernoulli effect means that regardless of throttle position, air is ALWAYS being pulled in through these holes and mixed with the air coming from the fender well. Their position is not really over anything "hot" though. I wonder if they are part of the silencer system?

I've never heard the "intake whistle", but we don't get very cold here. ;)

I'm tempted to tape over the holes with aluminum tape to see what happens. :)

- Jack

I think you're spot-on there... Instead of amplifying the offending frequencies, it helps dampen them.

I was wondering what kind of experiences Bill or any others have had with the volant cai?

Okay for anyone looking to do an upgrade to their air intake try looking at tru-flo sealed system. It retains stock air box and gets rid of that plastic intake tube, then is replaced with a powder coated tube over to the fender. So you can use any stock filter replacement that you desire or the one it comes with. Just a thought for some of us out there whose parts bins are empty.
-Lars

And, Lars, it sounds like this does not alter the stock MAF sensor enclosure in any way? I'm puzzled now that it would make your engine run poorly.

- Jack

MAF sensor location
 

Jack,
From what I have seen in some of these installs and test drives. It is no different then the stock system except the restrictive intake tube is done away with and a different stock size filter is used. If I was following Bill's description of the "gotts" system correctly or in that system is the MAF sensor relocated also. Another thing that is note worthy is very little to no droning noise. 4.2 and 4.6 have something different in their stock intakes over the 5.4 looked like a restrictive cone shaped funnel insert. Found that in a 05 4.6 STX and forgot what year 4.2
-Lars

By the way Jack great job on the snorkle tube post!!!
Loved the pictures!
For $13?
That is kind of what I meant when I said sometimes our parts bins are empty. There are some of us at sometimes in our lives that the packaged product looks like the shure thing, but if we put our mind to it like you did we can take pride in a job well done.

K&N
 

I got the K&N - works OK - only loud when I stomp on the gas otherwise no drone louder than the MBRP mufflers.
Only complaint is the fit between the box and hood - seems to me designed to seal between the top of filter box and hood but it like its not tall enough.

Has anyone tried the tru-flow system? I found them for around $130 and they look like they accomplish the same as thing the modified factory intake.

Actually, Lars, the real cost is on the order of $8.00 now. It was $6 and some change for the ABS tube and you can buy 3" hose clamps for 99 cents. So, since I didn't use the coupler in the final product, I don't count its cost.

The MAF sensor's environment is not altered in any way in my truck. It sits up above the filter box very near the throttle body and, as you can see, all the modifications took place about two feet from it. I know the filter housing design is completely different on pre-2004 trucks though, so the MAF sensor location might be different too.

I took my truck out for a bit of a spin today because I installed pressure monitoring transmitters on my valve stems. I wanted to see if they upset the tire balance. (They didn't). But, I stepped on the gas pretty hard a couple of times and there's no drone.

- Jack