ha ha - not sure about the versus!
Jacko - on my ZX6 I have a blue-flame exhaust can - its a road legal unit with twin outlet, I leave the baffle in the main outlet and the end cap in the lower outlet - this is the road legal status.
I have tried it with the main baffle out - very loud and fluffy running at the low revs
With the main baffle in and the lower cap out - slight increase in noise - generally runs OK.
With the baffles in place it is great - slightly louder than stock, same running, save a TON of weight (well, a good few KGs anyway)
But yes - the induction howl is really something on those bikes.
On the subject of air filters - I mentioned that the OE one was decidedly filthy looking and I doubt that the previous owner (or myself) have exactly taken the bike to any particularly challenging environments. Yet I was glad I had already bought a replacement at just 8000 miles.
on the other hand, my BMW 530d has just turned 31,000 miles, it is showing "4000 miles to service" (it was last serviced at 14,000 so 21,000 miles between services!!!) and it is still on its original air filter! - I'm not even sure if it will get changed at this next service either!
I know cars manufacturers are under pressure to extend service intervals for the fleet market - but this is ridiculous surely!?!? Because it came with the "service pack" (pre-paid 5yrs servicing - a bargain to specify when new) they won't even take it early - if the computer says 'no' - it ain't getting serviced!