morning Paul
I just removed the 6 Allen bolts to remove outlet pipe and perf tube came out with it , then drill out the pop rivets ( 4mm) and remove same end cap .
once apart I could measure the length of perf tube 400mm , and height and width of can , got my packing from Demon tweeks and they had a table of exhaust dimensions so you could work out how much to order
although my can was in-between sizes so just ordered the larger length and cut to requirements (did end up being about 1.5m length .
measured the thickness of the silencer metal and the end can aluminium cap then add 1.5 times pop rivet diameter for correct length and correct crush when fitted, mine were 4mm x10mm stainless steel pop rivets from ebay
I did order some 8mm length ones, as was concerned about a couple of then on the small part of can 12oclock and 6 o’clock positon might interfere with end pipe screws , but all was ok with 10mm length .
the aluminium end cap had got some erosion on the flange where it mates to stainless can, so cleaned up ( wire brush ) , primed with etch primer and a coat of heat proof paint ( stove, log burner paint, just what I had on the shelf ) hopefully should stop or slow down any more reaction between dissimilar metals and the elements .
Loosely fit perf tube in end cap
due to the oval nature of the can I first wrapped the perf tube with a 1m length of packing this was about the correct size for the smallest part of oval , I counted how many times it had gone around perf tube and then cut lengths of packing 400mm x 100-150mm from the other sheet of packing material , then unwrap perf tube and re wrap adding the strips at 3oclock and 9oclock position this now gave me a nice oval shape of packing , bit of masking tape to hold in place and it slid in nice , little bit a slight adjustment ( rocking from side to side ) of end pipe to get perf tube to engage with the other end in can and she was in , then just bolt up and pop rivet up and jobs done .