Well, its 4am and I finally found some part numbers!

the mufflers are to suit the EX250 series motorbike and will fit bikes like GPX ZZR and other parallel twins, and part numbers are as follows:

Yoshimura (full exhast system 2 into 1):
GPZ270SSC

Muzzys, 2 to 1 system (I think!?).
M-1401b

F1 series.
F1 F1-4080
F1r F1-4080r

Now, my question to you good people is this; how do I go about ordering the yoshi? do I just take the part number to a dealer and get them to order it or do I haveto order direct?

thanks for anyhelp on the situation.

p.s I'm already aware of the custom built ones in NZ, but I want to get a 2 into 1 system, and if I cant find that then I might not bother, or I'll try get neptune to make it custom for me.