Well I took on the task of removing the VFAD this weekend. It was my first time removing the front bumper, and it wasn't too bad. The information in the DIY section was helpful, and I had it off in like 15-20 mins. I wasn't exactly sure what I was going to find once I got it off, but it was pretty straight-forward. The VFAD is just held on with some quarter-turn plastic screws, and then the hardest part of getting it off was un-attaching the plastic vacuum hose that actuates the open/close valve. After I got it off, putting the bumper back on was easy, the hardest part was hooking the fog lights back up.

As I posted in the K&N panel filter thread, I put in my K&N last week, and removed the two panels inside the airbox. In short, I was dissapointed. I wasn't really looking for power, but I was hoping for a little more sound. And there may have been a little, but if there was I couldn't hear it over my exhaust. I was already planning on removing the VFAD anyway, so I was hoping that would increase the sound level.

If anyone doesn't know, the VFAD is a Variable Fresh Air Duct that mazda incorporated into the intake system. It is designed to give the car two different intake paths: one short and direct for higher RPM operation, and one longer and quieter for "normal" driving. In short it is supposed to provide better performance when your driving hard, and keep the intake system quiet when you just cruising. It does this by a vacuum operated valve that opens and closes between the two pathways.

Overall I am satisfied with the results of removing the VFAD. I can hear a growl from the intake now, even in addition to my exhaust. This is really all I was looking for, as I know there is not much additional power to be had from intake modifications.

Along with the sound though, the car does drive better. The engine responds quicker to throttle inputs. It feels a little torquier in the low and mid rpm range, and it feels a little quicker in the higher rpms.

I think one of the biggest improvements, though, is when I shift while driving aggresively. There used to be a slight hesitation when I engaged a higher gear and got back on the throttle quickly. Now there is no hesitation, it just starts pulling again. My hypothesis for this is that normally, the VFAD closes when you get off the throttle, and then has to re-open again after your shift. Without it, obviously, you don't have to wait for it to open back up. I don't kow that this is the case, just my educated guess.

In conclusion, if you're like me and you're on the fence about getting an intake, or if you're also like me and can't drop the $350 required for a REVI, do this mod. Matter of fact, even if you don't mind spending the money for an intake, save it and do this instead. You'll get 70-80% of the performance an intake would give you, for FREE! Well ok $43 if you buy the K&N like I did, which probably gives slightly better performance than the stock filter. Just set aside an hour or two, depending on your technical ability, and you'll be done.

 

Nice write up.
If you take the foam cushion and the plastic debris shield out, you might get even better results when in high RPM. Drilling the top half of the grill may also help a little.

 

Thanks man.

I did take the plastic debris shield out, but not the foam cushion. And I actually had my dremel in hand, thinking about drilling some holes in the grill, but decided not to. I didn't want to give too easy a path for water to get up in there.

 

I live in south FL.
When I had that mode (before putting on a turbo last year) I've driven through the entire rainy season without any issues. And i mean in the summer, you go back from work in a heavy rain 4 days out of the week.

You'd have to literally pour water into the intake, to have the engine choke.

 

If you just removed the vfad and did not bridge the gap to the radiator support you will now be sucking up hot air.
I suggest doing that.

 

I posted a thead about the hesitation when shifting,https://www.rx8club.com/series-i-tech-garage-22/will-short-shifter-fix-my-problem-124726/ i thought no one understood me!!

Your reasoning makes sense to me

 

Whats the VFAD look like? any pic's?

 

http://pixelshifted.net/car/100_2922.JPG

In exchange i will need to know your avatar image source.. for research purposes.

 

How did you unattach the plastic vacuum hose that actuates the open/close valve?

https://www.rx8club.com/attachment.p...3&d=1187610560

 

If it's the one I think you're referencing racingbeat provided a cap for the vacuum nipple.

You ignored my counter-request :P

 

Oh my bad lol Don't know found it on google.com