What are the difference between the T04B/T3 and the T04E/T3?

TO4B and TO4E are names of different compressor covers. TO4B has a 2.625" inlet and a 1.75" outlet, TO4E has a 3" inlet and 2" outlet. The bigger TO4S has a 4" inlet and 2.5" outlet. This does not designate the size of the turbo, you can have a large turbo with a TO4B compressor cover that will outpower a TO4E turbo, but more often than not the TO4E housing will be accompanied by a larger wheel.

basically the to4e has a bigger a/r which means slower spool up on a stock motor..
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