Just a comparison of the original (stock) HA exhaust and a Hooker 2 1/2" exhaust system (86-87 style)...
a four bolt flange was added to the 87 cat to connect the downpipe-
you mean exhaust system? It's a hooker exhaust kit,They fit 84/85 TRs also. I believe the Cat is a custom job with a universal welded in to the stock flanges. You can buy it at summit.com
I bought mine from Advanced Auto Parts- just look up the Hooker Exhaust system for a Grand National... and yes my catalytic is a 86-87 style with the square flange welded on (instead of slip fit)