Hi, just fitted my K2 version with a K&N air filter and the Motad - Venom stainless steel, eBay £195.00.
Very easy to remove the old o/e set and fit the new system, good quality stainless steel with all fixings and gaskets, easy to remove baffles.
Went for test ride and the bike was transformed

. Felt lighter, flick-able and a very nice exhaust note to match with no baffles.
No loss of power top end and no back fire on de-acceleration. Felt the bike could breathe
Overall: the cost was cheap (than a pair of o/e fitment) and the

it gives - who cares how fast, just enjoying the ride

and

)