I think I am going to go with the flowmasters. But isn't the catback and the stock exhaust the same size to begin with. If it is the same size and mandrel bent what is the advantage.

Mike

 

Well i live in a winter area. The weld seals the flange keeping out salt and moisture . Giving longer life at the union of the pipes. I didn't go with stainless steel pipe but with the aluminized pipe. Hope to get alot of years like the factory stainless system.

 

I mean as compaired to welding in the flows

 

It all depends on what kind of setup you are doing. I'm assuming you are going to just replace the muffler and not the cat back? I don't know the dimensions of the mufflers so I can't tell you if it's going to fit or not. Other then going to dual exhaust, the reason I changed the pipes is because I think the stock ones are either 2.25" or 2.5" and I wanted a bigger pipe from cat to muffler. I use a 3" pipe in there. Then i go from the muffler to 2.5" the rest of the way out. You should just take it to a muffler shop and ask them. They'll give you a free estimate. Pretend you are interested in them doing the work. Find out what you need to know and then do it yourself if you have the tools.

The catback and the stock exhaust are almost the same thing. Catback just refers to from the catalytic converter to BACk. Back being muffler and tips and everything AFTER the cat.

I hope this helps. If not sorry. Good luck on whatever you do.

 

If you look at your pipes underneath your truck, on the engine end of the giant muffler there is a clamp at the y pipe where the pipes come together after the catalytic converters. If you buy a cat back system, everything from this pipe back will be replaced. the end of that y pipe is 2-1/2". In flowmasters systems 17393 and 17394, there will be a long section of pipe between that y pipe and the muffler. the pipe will be 2-1/2" at the very end where it clamps over the y pipe, then it expands to 3" until it hits the muffler. the dual pipes coming out of the muffler are 2.5" pipe. they originally tried 3" pipes coming out of the muffler, but lost power on the dyno. T00 big of a tailpipe is not a good thing; not enough pressure, and atmospheric air can push back into the pipes actually increasing back pressure. With two pipes coming out of the muffler, the pressure is cut in half, so they should usually be smaller pipes than a system with a single outlet. In flowmaster's systems, with the long section of straight pipe ahead of the muffler, if you don't want the super aggressive super 40, you can cut off an extra couple of inches and put a 50 series truck/suv performance muffler in there with the same performance and same 3" inlet dual 2-1/2" exit. I had to do this yesterday, as my girlfriend was with me when I pulled my boat home the other day. She (and also one of my fishing buddies) refuse to listen to the 40 for 2 hours on the way to the lake. Super 40's and fiberglass truck caps don't mix very well. Outside the 50 has the same tone, just a shade less volume, but inside is a huge difference in comfort.

 

If you have a system custom welded in, should you have the shop replace the pipeing before the muffler with 3"? The muffler I am going with a 3" IN, dual 2.5" OUT.

~Colby

 

Why come out of a 2.5" y into a 3" pipe? I went with a weld in because I just dont think the extra cost of that stainless pipe and muff were worth it living here in mississippi and the aluminum body muffs come with their lifetime warranty . I forgot I am talking magnaflow here. Magna also didnt make a set up like I wanted. I went with a 5 x 11 x 22 2.5"si /2.25"do and sounds great and feels like i gained some. Got it done for $300 and didnt have to crawl under the truck to get it done.

 

So the Y section of the stock pipeing can be replaced with 3"? Would this be best for both performance and sound?

 

I am not sure but being that you are living in cali you should look into this, I just moved away from cali ,I think the Y is considered part of the emmission system so swapping it out may be a little illegal.
As far as if it would perform better I dont know over analizing that type of stuff doesnt really do anything for me.I do know staying with the 2.5" pipe wouldnt decrease the performance .I just wanted to hear my v8 some

 

Anything before the cats is illegal. Unless it has a CARB EO number. I ran into this prob with my stang

 

I would recommend the magnaflow over the flowmaster for a weld-in. The flowmasters were the BEST for 5.0 fords but have a metallic sound on most new applications. One of my friends has owned an exhaust shop for 15+ years and spends a good part of each day talking the old-school folks out of flowmasters, just so they don't come back in when they don't like the sound......I've listened to 100s of exhausts, and the magnaflows generally sound better (personal preference, of course!).

 

depends on the state and the area in the state. It's only illegal if you get caught.

 

This is a weld in Magnaflow