As an alternative -- the JMB cans from RC Showcase work very well on headers only 6" long- the DA50 should perform nicely on these.
I have run KS tuned and JMB non tuned cans on their 100 engines ( same cyl -I believe) --and these setups work well.
The power gain with a non tuned can may be very small but the noise reduction is very noticable.