Best gains in BHP come from ITG, Forge Twintake and EVOM's. For all of these you will have to lose the engine cover. On a Normal remapped GTI they have all been proven with back to back Dyno plots to give around 20bhp gain over the oem intake and panel filter. Carbonio still utilises the airbox in the engine cover, but has a pipercross panel filter for better flow. Gains on the Carbonio on a remapped GTI are around 7-9bhp over oem.
The ITG and the EVOM's are the loudest and can grate on some people who tend to like a quieter intake.
The Twintake is a good compromise between the noise of the two above and oem.
The Twintake looks the best IMHO, but it isn't cheap.
I have an EVOM's, which is very loud

RedRobin has the Forge Twintake.
