would this work then? take the new flange and get a straight through catless system made for the track. then its only three bolts to swap out the exhaust and put back on the street system with the cat still in tact. seems like it would work in theory
There were minor differences between the mid-pipe I had on my 85 and an 89 mid pipe. The 89 mid-pipe has the flange on it for an O2 sensor, however if you also have access to the exhaust manifold from the 89, you can remove the block-off plate from it and use it to block off the opening (or just leave the spare O2 sensor mounted on it to block off the opening). The location of the flex pipe and the support bracket were also slightly different. Aside from that, the general shape and flanges are the same, so using the one from the 89 really shouldn't be a problem.