The two 'end' discs can be seen by looking up the tailpipe and are after the fatter 'silencer' section (if you can call it a silencer, which it isn't really). The front disc is actually a full-blocking baffle with perforations around it, so the gases have to pass through the perforations to get over the baffle. This is primarily how it silences and why it simply doesn't flow.
I fitted a set of the factory 'noisy' pipes which are made without the 2 rear discs, but still have the front baffles in place. So in effect I just spent money instead of drilling out the existing discs from my original pipes. The car is noisier for sure and a little more perky, as they flow marginally better. But a full straight-through will flow best, although the noise increase will be significant, as Mr Dab here confirms!
Which is why I intend to get me one of those Garage-56 kits when they're available, as the exhausts are indeed straight-through, but with proper absorption baffles which do not restrict flow but will do a much much better job of silencing the engine. So with the opened up air-filter too, you can have your cake and eat it - as well as getting back the lost power that we all read about in those prototypes and early customer cars.
