Howdy,
I just got an 01 excursion 7.3,
I want to do some basic mods mostly for economy (and a little power). I am planning on opening up the exhaust, the freeing flowing filter element and the DP tuner, just looking at economy and towing, no big power.
I was planning on a 4" exhaust but after looking at the stock 3.5" it really doesn't look to restictive (other than the muffler).

My question- should I just do a low restriction muffler or will it be worthwhile to do the complete exhaust system?

I know the complete system should add a little power and lower ex temps, i just wonder how just a muffler replace would do in comparison.

Thanks

Jerry

 

You can do a muffler delete now to open it up, it will sound better and of course run lower EGT's, but it won't do as much as a full 4" will do. I'm assuming the EX is stock right now, so a muffler delete (welding or clamping in either a piece of 3.5" or flex tube) will benefit you with lower temps. When you do the DP, then you might consider running a 4" to help push out the extra fumes it will create.

 

Well consider that 3.5" in exhaust gives you 9.62 square inches of space, 4" gives 12.56 and 5" gives a whopping 19.63. What seems like a little increase in diameter makes a really significant difference.........or so i'm told.....

 

The exhaust is the most benificial mod you will do to your truck. Skimp the first time and all you will do is spend your money twice!
Go to eBay and check out the OBO items. I got my name brand exhaust for $400. You won't find much better than that.
PS - I here you can weld in a straight piece if you loosen the front section and flip it upsidedown (The orginal muffler is offset)

 

What does 7" equal?

 

I am going with 153.86" Are you really running 7"? There is a guy I pull with that is running 6" That is nuts! He built it out of semi exhaust.

 

No, not the entire exhaust, lol. According to ernest, 7" exhaust is TOO BIG and it would be like a watermelon effect in the exhaust.

 

A damned happy gal?

 

38.48......../with lime

 

Yes, you are right. Damned happy is about all i can describe it.

 

Well since nobody has said it yet, the biggest difference between 4 & 5" exhaust is just sound. You don't really benefit from 5" unless you get up over 500HP. Also, the stock 3.5" exhaust is not mandrel bent making the turns extra restrictive. Order one of those 4" aluminized MKO kits and don't look back. I wanted to spend a little more for the Stainless, but knowing what I know now, I'd probably go aluminized.

 

One thing that hasn't been mentioned yet..... The stock downpipe is only 3 inches. The rest of the system is 3.5". If you get a new exhaust, you can buy a system that is 4 inches from turbo to tailpipe.

The stock muffler is the cause for a majority of the restriction in the exhaust. The downpipe is the second piece of the puzzle.

 

Thanks for the info, makes a lot of sense then to go with a 4" turbo back kit,

Now which one and who has the best price?

Jerry

 

Look on ebay for a company named MKO performance. Alot of the guys on here have 5" systems from this guy that are sometimes a hundred dollars CHEAPER than a name brand 4" system such as magnaflow, or even an aluminized MBRP...

 

and don't waste your money on duals, i don't want to hijack the thread but what do the question marks mean in your sig kris, i thought you were runnin 6" mitre cut stacks