Cutdowns are often tuned – much like a four-wheeled hot rod – by overboring the cylinders to increase engine power or adding performance exhausts, modified carburettors, or aftermarket shock absorbers. Some enthusiasts replace the standard drum front brakes with hydraulic disc brakes or add water cooling radiators. Lambretta owners may replace existing parts with a Nikasil plated aluminium barrel with radical porting, large Dell'Orto or Mikuni carburettors and bespoke (custom-made) expansion chambers, hydraulic clutches, and modern low-profile tyres. Some scooterists use aluminum Fabrizi racing barrels, because they use a rotary induction mechanism. Stock gas tanks may be replaced with increased capacity tanks, which put the weight of the fuel further forward.