Exhaust cut out - best deal.

And the electric ones take soooooooo long to open/close; which is only a problem when the cop in the next lane rolls down the window and says; " excuse me sir but, um........ you are sooo busted."

And like already alluded to; open-exhaust slanty's can only be enjoyed by other slanty owners.

I agree about the sound of slanties...
That said, these ones I have only take 3-4 seconds to open or close.