You would be fine with the 4in. 5in will be louder and deeper, but for HP it's not needed unless you plan on making big power.

 

just like Jel said... you will not see any performance gains going with a 5" over the 4".... the 5" is def louder with a low deep tone...

 

Personally.... I find the best thing to do - is to not have anything connected to the turbo at all. Just have that chit spray all over the engine bay.

oke

 

Like they have been saying you will be fine with a 4in unless you want the deep note then go for a 5in exhaust. If you plan on pulling sleds though along with upping the power the 5in would be better it allows things to breath better which inturn as we all know makes more power. My dad had that issue hauling a dozer with his truck,it kept over heating on the interstate since he has a 4in with muffler so it doesnt breath as well where as mine with a 5in straight pipe stayes much cooler when towing at speed on major highways.Oh and if your gonna be pullin make sure your tranny can handle the stress, I have seen one to many stock trucks ruin there transmisions pulling transfer-sleds, I happend to be one of them. Hope this helps.

 

Sounds good. Thanks for all the info. What kind of trans work should I do anyways?? I would only pull maybe once or twice a year and other than that I just DD the truck and pull a trailer once in awhile.

 

If you want another option, you could just put a Walker Big Truck Muffler on the stock 3.5" exhaust for a free flow option, or just go straight pipe. 3.5" is plenty for stock to slightly above stock applications.
Trans work should a 6.0 cooler (or just a bigger one), a valve body (have a Factory Tech from Greg Evans), and an external filter setup is never bad.

 

4" has the same capabilities that 5" has, 5" just has a deeper tone. They both use 4" down pipes. oke

You can only flow as much as your smallest pipe....

 

5" definitely sounds better and is usually only barely more expensive.

 

Depending on what kind of kit you get, you may not be able to keep your spare tire under the bed (stock location) if you go with 5". Some 4" kits can have this problem as well. I did an MBRP 4" Cool Duals and was able to keep my spare. This kit added a nice tone but didn't make it really loud. I'm very happy with the MBRP kit.

 

I built my own 5in exhaust and have it dump right infront of the rear wheel. As for trans up grades get the 6.0 cooler like Jesilvas said and bully dog makes a Shift Enhancer for about $90 that will help with shifting for an auto. So it would benifit you in normal driving as well as pulling.

Here is the link for it.

Bully Dog Technologies - Diesel and Gas Performance Products F-SERIES 250-550

 

If your considering switching tuning already don't bother getting another programmer for shifting, just get the PHP as they can put shift points right in the tune if I am not mistaken.

As for the exhaust 4 or 5" don't really matter, Just sound difference until you start talking some real numbers. If you like the deeper sound and don't mind a few extra bucks get the 5" to leave yourself open for later mods.

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