The length of the trumpet will impact/move the power band. Typically shorter trumpets move the power band to the higher RPM range while longer favor low and mid-range. These look shorter than the stock S54 trumpets.
The most ideal setup for ITBs is an airbox big enough that channels fresh air from outside the engine bay. The screens don't do shit for filtering dust particles. The socks that slip over the trumpets hurt power because they disrupt the laminar flow created by the velocity stack itself.
The stock setup is actually pretty good. The only weak link is the MAF and the smaller air inlet when compared to the CSL box. This is why CSL box is good for about 5-10 hp. But that is usually with tuning since you cannot just remove the MAF from the equation and go.
Removing the MAF requires tuning. IAT needs to still be utilized for air temp correction. Having it as close to the throttles as possible is most ideal. The general belief is that you need to use Alpha-N tuning, which is MAP + TPS based enrichment tuning, but you can tune an ITB car with just TPS. If retaining the stock ECU, then Alpha-N might be the only option to play nice with the rest of the ECU's parameters. On a standalone ECU, TPS only is fine.
I have a highly modified ITB Miata that I have developed over the last 9 years. I am pulling 185 whp out of a stock piston and rod bottom end. Stock is 140 crank and dynos around 110-115 whp. So I have done a great deal of research with ITBs and filter options, etc. FWIW, it's the highest horsepower stock rotating assembly Miata in the world.
I run what's called a sausage filter, which provides enough free space around the trumpets and actually does not impact horsepower. The only downfall is the warmer air from the engine bay, but my IATs do not get very hot when the car is moving. An airbox ducted to the front would have required more cutting than I wanted to perform on a car that I built to be driven on the street.
IMG_20151030_231645 by
Maximus5891, on Flickr
IMG_20151013_003009 by
Maximus5891, on Flickr