Double clutch, you rev the engine in neutral....why dont was just step on the clutch...rev the engine with the clutch in and shift to the lower gear? Does it have to do with the layshaft???

 

Not sure what a layshaft is, but the reason for double clutching is to synchronize the gears as if you had no synchros.

 

I guess what Im asking is...why do we match revs in neutral? why not match revs with the clutch in?

 

If you keep the clutch in, all you are doing is speeding up front plate of the clutch (the part that is connected to the engine). The reason for double-clutching is to speed up the shaft that is connected to the rear plate of the clutch to match the speed of the shaft that is connected to the output of the transmission (and to the wheels).