Thanks. I might not been needing the assembly paste after all. It looks like the 1997/1998 Mk1 MX5/Miata might have a longer cat than other years. Meaning that my nice new exhaust won't fit without being cut down, which makes it a job for someone else...

I didn't drive it back, I had the AA recover me back home. If I had driven another 160 miles my bumper would have been a puddle of black plastic...