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Discussion Starter #1
Will the 9C1 Y pipe fit on a 1993 Roadmaster Sedan? I'm considering a single exhaust and wondered if it would work in place of the restrictive factory one without a lot of fabrication. I would also lose the CAT.
 

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You already have a single exhaust. The 9C1 Y pipe will fit the 93 RMS without modification, and you will not loose the CAT. It will not yield any noticeable difference in performance. If you got the cam, injectors, computer, and pipe out of the 9C1, you would be able to pull 205HP from the engine.

It is not particularly simple to swap the cam, but can be done in the car. You have to remove the X brace, and the vertical brace on the core support, as well as the radiator, and the condenser. You can wiggle the timing chain cover off without removing the pan, but it is not recommended. You should at least drop the pan an inch to free up the seal on the bottom of the timing chain cover. You will also have to remove the intake manifold (and all the other parts associated with it), and the lifters to swap the cam.

Putting dual on the car would give you about 20 HP, but you will have to make a hump for the driver's side pipe in the trans crossmember. You will loose the cat on the driver's side, unless you can get the parts from an LT1 driver's side, but then you will need the heat shields from the LT1 car as well. If you use shorty headers maybe 30HP total with the same driver's side cat situation, and you will have to relocate your O2 sensor and the oil pressure sender. Each part you change will require a couple of modifications. If you do not want to make a hump in the trans crossmember, you can run frankenduals on the passenger's side, but you will not have room for the CAT. You should put a washer the thickness of a quarter under the spring in the fuel pressure regulator to feed the added fuel necessary, or use the 9C1 injectors, for any mods in this paragraph.

Once you go beyond the above, you need a custom chip for the computer.
 

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Discussion Starter #3
Thanks for the info!!

You already have a single exhaust. The 9C1 Y pipe will fit the 93 RMS without modification, and you will not loose the CAT. It will not yield any noticeable difference in performance. If you got the cam, injectors, computer, and pipe out of the 9C1, you would be able to pull 205HP from the engine.

It is not particularly simple to swap the cam, but can be done in the car. You have to remove the X brace, and the vertical brace on the core support, as well as the radiator, and the condenser. You can wiggle the timing chain cover off without removing the pan, but it is not recommended. You should at least drop the pan an inch to free up the seal on the bottom of the timing chain cover. You will also have to remove the intake manifold (and all the other parts associated with it), and the lifters to swap the cam.

Putting dual on the car would give you about 20 HP, but you will have to make a hump for the driver's side pipe in the trans crossmember. You will loose the cat on the driver's side, unless you can get the parts from an LT1 driver's side, but then you will need the heat shields from the LT1 car as well. If you use shorty headers maybe 30HP total with the same driver's side cat situation, and you will have to relocate your O2 sensor and the oil pressure sender. Each part you change will require a couple of modifications. If you do not want to make a hump in the trans crossmember, you can run frankenduals on the passenger's side, but you will not have room for the CAT. You should put a washer the thickness of a quarter under the spring in the fuel pressure regulator to feed the added fuel necessary, or use the 9C1 injectors, for any mods in this paragraph.

Once you go beyond the above, you need a custom chip for the computer.
 

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Another possibility is to run a pipe from each manifold to the right side like it was going to be a Y pipe, but make them separate and connect them like a 2 into 1 header collector, then feed them into a single 3 inch pipe from there back. You could even partially flatten the 3 inch pipe to give you extra clearance. If you must have a cat, you could use a large diameter intake/exhaust cat to keep your resistance low. It would have the same effect as a dual exhaust.
 

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Discussion Starter #5
If I had the skills and equipment to do it myself, I would do what you suggest or put on duals, but the motor only makes 180 HP and I don't have plans to increase the HP. So, based on my budget for the project, and what my mechanic recommended, I decided to have him put a straight pipe in place of the cat, replace the stock muffler with a Magnaflow, and stick with a single exhaust. I'm happy with it and was nicely surprised today how well it sounds with just a single exhaust.

Another possibility is to run a pipe from each manifold to the right side like it was going to be a Y pipe, but make them separate and connect them like a 2 into 1 header collector, then feed them into a single 3 inch pipe from there back. You could even partially flatten the 3 inch pipe to give you extra clearance. If you must have a cat, you could use a large diameter intake/exhaust cat to keep your resistance low. It would have the same effect as a dual exhaust.
 
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