I'd guess they are valuable by now, Good buy. The 300's were considered better performance wise than the 341's. Paragraph pipes are more correct on some bikes, I'm thinking they began in mid to late K0 and went through K1 or was it K2?
The new ones we can get now are unstamped. No paragraph as far as I know. Less trouble with copywright issues and the early ones weren't stamped anyway. I put a set on my sandcast 2 years ago and recently got a set from DSS. Their price is close to Yamiya but shipping is $18 compared to $250 from japan. They are the same pipes either way. Mine both fit nicely, sound good and I've had no other problems aside from getting a mixed up set, they fixed that right away.
I remember the old ones rusting quickly so I coated them inside with Eastwoods inside stainless exhaust paint. It comes with an 18" extension and 360* nozzle. Of course I removed the baffles first and checked the drain holes to be sure they remained open.
