New exhaust pipes with shorty mufflers

Changed main jett to a 90, got her running alright. I have my fuel mixture screw 3 1/2-4 turns out to try and decrease my decel popping. I got it to go be less aggessive. Any recommendations for getting it better? I understand im runnning 12" mufflers so it may be inevitable. Let me know what you guys think of the new look. 

Also, any recommendations for holding slip on mufflers on? i have a u clamp on it and it does alright, i dont want to weld because i want to be able to change my muffers if i need. 

I was looking for a new chain to but struggling to find the exact part number online. Does someone have a link for a chain I could use? 
 

You can probably find chain and sprockets here —  www.z1enterprises.com/drive-train-and-tr...duct_list_order=name

It would help us give better advice if we knew exactly which year and model you are asking about.

Also, are any modifications to your bike besides the mufflers?

its a 1978 kz400b, and besides the mufflers i bought a pair of headers from ebay. thanks for the reply!