What exhaust collars?

My GPz1100 has a J series head. The header that I took off had the long flange and collars that don't come off, so I need collars and those half-circle inserts for my exhaust system. So, what collars besides J heads (for instance, '82 and later 1000P)will fit? Will Z900? KZ1000? Particular years? Help!

im thinking you are stuck with j/gpz style split collars they are differant length.i think you can use the outer collars from kz1000 z1/900 outer collars have smaller holes for exhuast studs.

Are you saying that it's the split collars that's my problem? Looking at the collar/clamp/chunk of aluminum that the studs go through Z1 sells a replacement, but they also say that it retro-fits to earlier KZ1000's, so I'm thinking that I could get some of those to work. So the only NEW parts I need are the split collars? Is that what you're saying?

yeah ive got some gpz-j style collars ,let me measure real quick.ok about 29mms for the gpz style split collars is what you need.kz1000 outers should be same size z1/900 are smaller.