i am running 2 1/2 dual exhaust on my car that runs down the outside of the frame right under the doors and exits right in front of the back tires. are there sfcs that run inside the frame rails? or does anybody know of some that will work with this setup?

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92 z28 170,000 miles 14.20 on goodyear eagles only mods k&n and muffler fell off!
87 trans am 12.20 on motor too many mods to list