Guys.
Just been reading through this thread, and thought I would add my 2 cents worth.
Cold Air Induction........ Air Filter...........
Cold Air Induction.
You will be lucky to see some or if any, gains on the dyno from running a cold air intake alone. If you do, the readings will be very low. The Ram Effect as mentioned earlier, is only valid when the air speed into the intake is in excess of approx 130kph (by memory, I think it's even higher). The ducted fan placed in front of the car during a dyno, does not push air speeds that quick, so the ram effect of the Cold Air Intake is pretty much nil. Where you will gain and notice this mod, is when you actually drive the car at those speeds or above. The cars response will be sharper (due to the air getting rammed into the intake instead of being sucked in)! Also, the intakes are usually feed from the outer most point of the car, eliminating hot air from under the bonnet.
Air Filters!!!!
If the cars standard air filter is restrictive (which most are), or the opening into the air box is too small (some are), this will throttle back on the amount of intake air the car is trying to suck in! An aftermarket air filter is usually the first place you will find intake increases, due to the fact that air passes more freely through these filters! This is a gain that will show up on the dyno. An easy way to tell if you have a restrictive intake, is put your car on the dyno and run it, then pull your airbox cover off your airbox, and run it again. The increase you get (if there are some) will help you justify if you need to update the standard intake/air filter set up! And that second figure you obtain on the dyno is what your approx. going to get if you upgrade your intake.
People will usually hear the 'intake hiss' when the car is running, after they have changed the standard Air Filter. This goes to show that it was fairly restricted in the first place, if this is the case!
I can't remember the size of the 5.4 airbox intake hole. I chopped mine a month or so ago to accommodate the SS induction. By memory, I think it was small (for the 5.4ltr motor that is). Unfortuntely, I didn't put this car on the dyno with just the whole intake upgraded, then again with the exhaust upgraded. I did however, did a before and after dyno. Standard = 196rwkw, Cat back Exhaust & Air intake/BMC filter = 206rwkw. Same dyno, same operator (of who had nothing to do with any of the modifications).
Hope this info helps!
AGRO!!!!!!