From Club RSX
The K20 ITB's only come as a complete system:
The 48m/m system is $2135.oo usd
50m/m system is $2395.oo usd
52m/m system is $2510.oo usd
54m/m system will be a custom, so the cost will be reflected in it's price.
The system includes:manifold,throttles,linkage,hookup for stock RSX throttle cable,fuelrail,airhorns,TPS and wiring clip.
The vacuum tree is built in to the intake flange, which is the same as the stock manifold, using a passage within the cylinderhead mating surface.
The ports for the vacuum are on the side of the # 4 runner, same as stock, vacuum ports for power brakes and map sensor.
For your uses, the 48m/m would probably be the best choice to retain your low end torgue/ drivability etc.(road racing)
The overall length of the system is such that a 40m/m tall airhorn is used, as the manifold is longer than usual so as to position the throttles correctly to clear the power steering etc, this system still has the same overall length as my S2000 system which uses a 90m/m airhorn.
The K20 system is not on the website yet, as I have a bunch of changes to make on the site, and I am waiting for one supplier to get me some larger airhorn parts,52m/m and 54m/m, so I can get some good pictures of the K20 system for the site.
As for an airbox, sorry I don't make airboxes, as it would be a never ending story, as one airbox will not fit all the applications that I sell.
Andy