If you have a car and love speed, then you are quite familiar with induction kits. These are cone shaped filters that help increase a car's air intake thus increasing the horse power in the process. Performance Air Filters are an excellent first time performance modification when you want to tune your car. Such kits are often required by speed racers and are used when fine tuning a car or increasing its racing capabilities. Basic panel filters from K+N, Pipercross and BMC simpley replace the original paper filter with a high flow filter that is the same shape and size but is designed to allow more air into the engine to increase power while still cleaning the air that passes through. The most popular performance air filter is an induction kit that generally replaces the cars original airbox with a tailored cone filter. If space allows these induction kits will have a separate cold air feed from the front of the vehicle. For the ultimate in performance a closed airbox with a performafilter inside shielded from under bonnet heat sources is the way to go. Pipercross Viper, Venom, ITG Maxogen, K+N Apollo and Typhoon are closed air intake systems which will produce noticable power gains. Research has shown that cold air induction encourages more cold air intake in the car engines -more oxygen- which further results in the car's speed increasing significantly. Thankfully, cars these days come with that allowance thus giving all intended drivers the opportunity to increase their car's speed. In all cars induction kits will suffer from under the bonnet temperatures. We all know that hot air carries less oxygen. Removing the air box makes the intake temperature rise as air is taken from this hot region. Most dyno runs are taken with the bonnet open so will not reflect real world power gains. To combat this problem add a cold air feed to pipe in fresh cold air from outside the engine bay. It is worth noting that not all engines will experience power gains from an induction kit. Smaller engined cars (those under 1.4 especially) will actually feel less powerful with an induction kit. In this case you should use a panel air filter which replaces the standard paper one inside the OEM air box. In these smaller engines a certain amount of excess oxygen will not be matched with fuel as the injectors are not big enough. This causes the engine to run lean. An air filter should also be matched to a good exhaust system to allow a balanced flow through the engine. More air in means more exhaust gases. Now that you understand induction kit better, a good place to check them is http://www.aktivperformanceparts.co.uk. It a one stop shop for all your induction need. The patient staff is more than glad to respond to your queries and make you understand intrinsically about induction kits. We love our cars and know how to treat them royally and pamper them!