most aftermarket CAI's are similar, a straw with a filter on the end. AEM has a powerchamer design, a straw with a step up dia straw and filter. At least both are better than the sri design, drawing air from the hellish temps by the header.
If you are down with relocating the battery or getting an Anti-gravity tiny battery unit, passwordjdm sells a carbon fiber powerchamber intake that gets good reviews. still it draws air from the engine bay.
For the most part all CAI intakes are equal and they draw air outside if the engine bay from inside of the fender. Due to the length of the longer tube, CAI tend to make more mid to top end gains over lets say SRI or Mugen style OEM airbox units and OEM airbox mofication systems with a Spoon air filter. the Spoon air filter is $200...ouch.
The ticket is a ram air style intake system. The are a few expensive units - Gruppe M and Mugen. They combine the low end and mid-range powe gains with the top end gains from cooler denser air while the intake valves are open for shorter durations.
I am making a ram air intake that will have the length of a short ram intake and have a seperation box/pressurized box feed from the fender by a scoop and aluminum duct work.
Sorry for.the essay, on a budget or condvience of buying a intake unit any CAI will work, I would try AEM dual chamber unit
As air travels through a pipe friction happens against the inside wall surface. Attempting to keep the pipe cool will cause the air to travel faster. Insulating the pipe can only help.
So the larger the pipe the more friction takes place, so keeping velocity is the key. The right size TB, right dia pipe, cooler inside wall surface and intake design make good velocity and less frictionm if there is a transition piece it needs to be smooth and not abrupt right next to the TB. some pipe on the smaller dia side at least 3" long will help with velocity.