i know for other cars with aftermarket turbo they require turbo timers or atleast have to let their engine run for a couple minutes before turning the ignition off. is this required for the 135i''s, 335i's, 535i's?

 

Nope, not required.

 

It's a good idea on any turbo to ensure that the last few minutes are driven at low loads and revs and then to let the engine idle for 30 seconds before shutting it off. This lets the turbine/compressor assemblies slow down as much as possible before their supply of fresh cooling and lubricating oil is cut off.

A turbo timer would be very difficult to install on a new BMW due to the high level of integration between the engine management and locking and alarm systems.