Ive got a new catalytic converter on the Willy now and Ive come to a conclusion. Its definitely quicker without one (particularly over 4500rpm). The engine doesnt feel strangled or anything with the cat on, it just feels a lot more free at high revs.
I would recommend a silenced de-cat though as the buzzing that a straight through pipe makes is just fecking annoying and sounds sh*te!
Rhys
