Yeh your right R1's go 4-2-1 but the 2 is is about 2inch in length at best, I wouldn't mind a comparison though

 

I can't say I know why, but if it were "cheap" to go to the 4/2/1 configuration...why wouldn't the aftermarket go 4/1?? I wouldn't classify any of the big name full systems as "cheap"

 

That's a good point.

I think we were both comparing them to car headers, where generally a 4-1 header is MUCH more expensive than a 4-2-1 setup. It is definitely expensive for a full setup, though.

On the flip-side, my Kat has a full V&H 4-2-1 and it picks up power in the upper end - (V&H exhaust + K&N box + jet kit) - it's actually a bit flat in the lower revs (forgot exactly where the flat spot is - only for like 500rpm mid-range or something).

 

Volume vs Velocity, just as it is with short and long intake runners. A 2-1 collector helps increase exhaust velocity (opposing exhaust pulses help create a scavenging effect) which is beneficial to low-mid range where 4-1 is about moving as much volume as possible which benefits top end.