I just received my Magnaflow 15679 SI/DO catback system. I also ordered 2 Magnaflow high flow cats. I need to know if I have everything I need to install these products or if I am missing something, new "Y" pipe or piping. After searching the board, I saw some horror stories about the factory pipes restriction. I guess my question is this, by replacing the 4 stock cats with the 2 high flow cats, is replacing the factory "Y" pipe necessary or optional? I think it is probably a good idea after seeing how the factory "Y" pipe is made. Magnaflow has a 2½" Dual In / 2½" Single out "Y" pipe p/n:10768, is this what I need? Will I need extra piping? I am not sure if when the 4 cats are removed, that the 2 new high flow cats will change the way the exhaust is routed to the muffler. Any help is greatly appreciated.

 

If you are repalcing the cats and rest of the exhaust, I would change the Y-pipe too.

Take a look at that Magnaflow DOR system The front pipe before the muffler, does it get larger? on the 3" single system, it is 3" through the muffler and the tailpipe. It just has a reducer at the very front to bolt onto the OEM exhaust at the y-pipe. Does the dual system do the same thing or is it all the same diameter? The reasons I ask is because I would probably get a dual 2.5" in to 3" out and cut out the reducer on the muffler back system. Otherwise, 2.5" all around would be easier to install.

 

APT, the whole system is 2½" (All pipes, muffler inlet and outlets) so I think I would need the "Y" pipe p/n:10768 (2½" in and out). Guess I should have just pieced together a custom true dual system, but I was originally looking for the ease of a bolt on system and the only real reason for the new cats is to get a little more sound out of the exhaust. Anyway, too late now... If I go with replacing the cats, getting the new "Y" pipe and bolting on this kit, will I need additional pipe to replace before or after the cats? I am not exactly sure how replacing the 4 cats with 2 will affect how the piping is routed or what else is need to accomplish the job. One more question, can the new system be bolted on before getting the cats and new "Y" pipe in or is it best to do it all at once? I wanted to bolt the kit on, then take it to a shop to put the rest in. Also this would give me an idea of how it sounds before and after the new cats.

 

The 15679 should bolt right up after the factory y-pipe. I just don't knw about how you are going to hange the new pipes as I don't know what came with the kit.

After you get that done, I would order a 90* mandrel bent elbow and that 2.5" all around y-pipe and install when you do the cats. #10768 and #10706.

When you replace the cats, you'll need more pipe which the shop will have in stock. I don't know if you'll need any extra pipe between the new y-pipe and #15679 system, but I have a feeling no.

 

Thanks APT, as you can tell, I don't know exhausts that well. I will bolt on the kit first, then see what I need to do the rest of the install. Have to find someone thats willing to replace the cats for me .