exclusively dry nitrous systems due to the non-optimal fuel distribution possibilities of the bar. Bar nitrous systems are popular with racers that prefer their nitrous use to be hidden, as the nitrous distribution method is not immediately apparent and most associated components of the nitrous system can be obscured from view. Propane or CNG Nitrous systems can be used with a gaseous fuel such as propane or compressed natural gas. This has the advantage of being technically a dry system as the fuel is not in a liquid state when introduced to the intake tract. Reliability concerns The use of nitrous oxide carries with it concerns about the reliability and longevity of an engine present with all power adders. Due to the greatly increased cylinder pressures, the engine as a whole is placed under greater stress, primarily those components associated with the engine's rotating assembly. An engine with components unable to cope with the increased stress imposed by the use of nitrous systems can experience major engine damage, such as cracked or destroyed pistons, connecting rods, crankshafts, and/or blocks. Proper strengthening of engine components in addition to accurate and adequate fuel delivery are key to nitrous system use without catastrophic failure. In addition, nitrous oxide should not be used in vehicles with an automatic transmission, as the highly increased engine power and torque may cause stress damage to the torque converter and the transmission itself. Street legality Nitrous oxide injection systems for automobiles are illegal for road use in some countries. For example, in New South Wales, Australia, the Roads & Traffic Authority Code of Practice for Light Vehicle Modifications (in use since 1994) states in clause 3.1.5.7.3 that The use or fitment of nitrous oxide injection systems is not permitted. In Great Britain, there are no restrictions on use of , but the modification must be declared to the insurance company, which is likely to result in a higher premium for Motor Vehicle insurance or refusal to insure. In Germany, despite its strict TÜV rules, a nitrous system can be installed and used legally in a street driven car. The requirements for the technical standard of the system are similar to those of aftermarket natural gas conversions. Racing rules Several sanctioning bodies in drag racing allow or disallow the use of nitrous oxide in certain classes or have nitrous oxide specific classes. Nitrous is allowed in Formula Drift competition.