YS Pipe Tuning
 

https://cimg0.ibsrv.net/gimg/www.rcu...33bf8d4685.png
I make aluminum pipes for my YS engines, this is just in case I put one in the ground it doesn't tear up the threads in the cylinder head like it will with the stock threaded (steel) exhaust pipe.
So I was wondering does it matter how long, or short I make them in regards to the changing the performance of the engine? Any additional information would be greatly appreciated.