Hello there, speed maniacs 
I'm just letting to know, that I make some special parts, mainly for Russian KO race engines, but they fit also on their Chinese cousins.
Expansion pipes:
a: low pipe design - paper template kit available, price 25EUR
b: high pipe deign - paper templates 25EUR
laser cut 0.8mm stainless steel sections - 45EUR
Both have the same characteristics, having just different curves.
I can make complete pipes also, but I cannot guarantee that they fit your bike. Also pre-made complete sections can be done.
Stainless steel reedvalve housing for KO engine:
Top and bottom plates are 2mm and sides 1mm.
This fits _only_ Russian engine case and smooth suface with square hole needs to be machined.
http://static3.nagi.ee/i/p/641/63/16040945ed44b1_l.jpg
Price - 30EUR
I'm just letting to know, that I make some special parts, mainly for Russian KO race engines, but they fit also on their Chinese cousins.
Expansion pipes:
a: low pipe design - paper template kit available, price 25EUR
b: high pipe deign - paper templates 25EUR
laser cut 0.8mm stainless steel sections - 45EUR
Both have the same characteristics, having just different curves.
I can make complete pipes also, but I cannot guarantee that they fit your bike. Also pre-made complete sections can be done.
Stainless steel reedvalve housing for KO engine:
Top and bottom plates are 2mm and sides 1mm.
This fits _only_ Russian engine case and smooth suface with square hole needs to be machined.
http://static3.nagi.ee/i/p/641/63/16040945ed44b1_l.jpg
Price - 30EUR