Hi Hen,
I had a staintune 4-2 exhaust on my 78E. It ran Ok. Luck passed me by and I ended up with a brand new still in the box exhaust system from Yamaha. To say that the difference in performance and power was noticable is an understatement. My bike transformed instantly in terms of smooth power throughout the rev range, was measurably quieter and just sounded better.
I am now trying to track down an original system for my RH. I think the only place I'm going to find one is in the US. Thus far nobody has been willing to go through the hassle of boxing up and shipping to Australia for a "reasonable" price.
Good luck with your search.
Eddy.
78E (sunny sundays)
81 RH (transport)
81 RH (Parts)
81H (Project in 1 million pieces)