Ultimate air box mod necessary?

I have an 08 WRX that is on WRR wheels. I'm planning to be riding a lot more dirt this year. I currently have the airbox door removed and it did help me considerably. I was looking at wrrdualsport.com's ultimate airbox mod and am not sure I want to go this route. Is it going to help even more than the airbox door and the AIS removed or is that enough alone? I also considered building an aluminum plate with a hole in it to go where the baffle is on top the airbox to get some more room under the seat for my programmer.

Mods are:
FMF programmer
FMF pc4
AIS removed
UNI filter

If you are going to ride it with the airbox side door removed, the airbox is already opened-up quite a bit.
I do believe the guy who first posted with the "Ultimate Airbox Mod" shortly after the WR-250R and WR-250X came out kept his side door on.

What I would do is to service the air filter after every off-road ride.
Period.

I don't think it is an absolute must do even though I have done it. That being said, there is a flapper valve that you may want to remove or modify so that it stays open all the time. Then again that is not a must do either.

I think the only disadvantage of riding with the air box door off (aside from leaning out the fuel mixture if you don't have a programmer) is the increase risk of water ingestion during a water crossing. The advantage with the ultimate airbox mod is that the water level would have to come up and over the airbox before you run the risk of pulling it through the intake.

If you won't be doing many water crossings the airbox door removal is the simplest and most easily reversible mod you can do to improve airflow. Ar times I will remove mine as long as I am riding in my local area but any time I head up north into the mountains I put it back on since I usually end up crossing several streams.

+1 on the air box is getting lots of air with the door off, opeing it up more wont help power at all.

I cant ride with the door off as ride in wet conditions alot.

If you want the same amount of air flow with the door on do what I did.

I did a version of the ultimate air box mod, you can simply get rid of everything under the flapper and the flapper itself by putting a screw driver into the hole the flapper actuator was in and hit it, the whole flapper and baffle part will fall into the airbox, this is waaay quicker and easier than all the cutting and grinding he did, plus you could glue it back on and go back to stock if you ever wanted.

IMO the ultimate air box mod is not that ultimate, the opening is not big enough so I cut a 2 by 2 inch hole right above the filter as well, this area of the airbox is protected from water better than the stock opening so dont worry about adding a hole there.