do i need an aftermarket bov and what is the difference between a after market and the factory bov (thinking of changing back to the factory bov is the a bad thing)

 

You only need a different DV if the OE item can't cope with increased boost levels after serious modding. Most aftermarket DV's are VTA (vent to atmosphere) where the excess boost pressure is release out of the system. The OE item is a recirculating design which feeds the air back into the system. The excess boost has been measured by the MAF and AFR and so by loosing it completely out of the system the engine runs rich very briefly, causing potential borewash, backfiring (which can cause cat damage and unsettle valve action through negative exhgaust pressures) and eneven running; the sudden pressure drop can also stall the turbo which isn't very good for it. The OE item puts the air back into the system helping slow the turbo and maintaining a better fuel/air ratio, which will prevent all the above and keep your car running much smoother. The only real reason most people have a VTA is so they can imagine a bus doors opening each time they change gear, or to impress the chavs as they drive by.

 

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