Our 4in race air box system has been designed for extreme power levels. The air box uses a massive 6in internal diameter K&N filter which mounts onto a 6in to 4in bell mouth which connects to a internally wire re-enforced molded silicon hose down to the turbo. This combination gives maximum flow for power levels of 500rwkW+. The air box can also be used for high mount turbo configurations. The 4in OD air box outlet is at the approximate height of most high mount turbo compressor inlets so a simple section of pipe is all that is needed to use the air box for high mounts. This is for those that have upgraded their turbo to a 4in inlet (0.7A/R cover), as supplied is the "4in to 4in" silicon hose. K&N Filter Supplied 6" to 4" bell mouth Utilises the stock location for the battery Suites upgraded turbo housing