Some of the holes will be oblong, you might need to trim the rear side of the crossover pipe to get them to fit.
I suggest O2 bung being welded onto the crossover. Its better than beating the **** out of your car to get the primary O2 to fit.
I would just beat the tunnel a bit. Its free and takes like 5min. I bet you cant drive to the welding shop faster than that, or even weld one in at home that fast.
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