The top deck series by Mugen Seiki consist of 2.0mm, 2.2 and 2.5mm top decks. The MTC3 kit comes with one 2.0mm and one 2.2mm top deck. Being able to run different combinations of top decks allows for fine tuning of front to rear flex and roll characteristics.  It's imperative to have these parts as they are a crucial tuning option. We recommend you have at least the following in your pit bag:

x1 2.0mm top deck
x1 2.2mm top deck
x1, 2.5mm top decks (often used in the rear to create more stability, can be used on the front for more high speed stability through long sweepers)

often the front top deck can break on high impact crashes, this is common with any brand of car and the MTC3 is no different. We suggest you have at least one spare 2.0mm top deck as this will be commonly used up front for most Aussie race conditions. Higher grip surfaces may benefit from a 2.2mm up front as this will create better mid corner steering.