Agree with G-Man. The silencers/mufflers are fine but the downpipes are not great, I have bought 2 sets of downpipes, I had to send the first set back as I could not get one to fit because the angle on the flange was slightly different and I could not get one to fit with the silencers I was using which did not use a sealing ring, The second set I bought recently was to go with the David Silver silencers, on one of these the flange was too large to fit in the head. When they measured others in stock none of them seemed to fit so they gave me a discount and I ground down the flange to fit myself. They fit OK now and really I think there is nothing else available unless you can find some good originals.
I have so far failed to get the baffle out of one of the silencers but given the mileage I am likely to do, it will probably never be a problem.
I got some stainless ones made a while back and I am going to see if I can get some mild steel ones done.
Even in quantity they are likely to be (at least) 2x the price of DSS ones. I'll make some enquiries and see what can be done.
'60 C77 '60 C72 '62 C72 Dream '63 CL72
'61 CB72 '64 CB77 '65 CB160
'66 Matchless 350 '67 CL77
'67 S90 '77 CB400F