I've been doing some research on these but haven't made a decision yet. Flowmaster part# 15818

Are these more trouble than they're worth or do they fit nice and provide good clearance?? I have a 9 inch rear and the axle tubes are larger than a 12 bolt. The car sits about stock height and has a 454 in it now but will end up with a 489 or a 496 depending on the bore.

The 2.5 inch are cheaper but will require a reducer at the muffler exit with 3 inch in and out. Was considering a 3 inch x with the race pros since everyone says they're quieter. Header flange is 3.5 inch.

These 3" exit pipes are from Torque Tech. They are very tight and there is some minor evidence of some contact with my 9" tubes, but I have never heard or felt anything.
If the FM's don't work out for you, this is another consideration.

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