Hi John
Just thought I would add these two pics of my first attempt at a rear entry exhaust.
The pipe was extended just under the rear arch then into another silencer box under the boot exiting out of another small sound reducing silencer box. It all worked well and sounded great, the only problem was it was too low at one point next to the axle IIRC.
I did go to Newark with this setup and was fine but it was mostly dual carriageway and motorway, but on country roads etc , the exhaust pipe was grounding badly over bumps.
The R1 can I fitted was great when I first fitted it but it was a freebie of a friend which had seen better days ,