I am thinking about 5" straight pipe. I just want to know if there is any down side performance wise. I am running a programmer and i have an aftermarket intake.

 

You will not see any performance issues. I wish I would went with a straight pipe. I have a muffler. The only problem that you will have is compressor surge in the turbo, which can be easly fixed with a WW or a new ATS compressor housing. Hope this helps

 

Just to help clarify, the exhaust upgrade will NOT cause compressor surge. New exhaust will lower your EGT's from the programmer. Plus with a 5' straight pipe, it's going to sound like nothing else.

 

Pocket what caused my surge then. It wasn't there with my stock exhaust and intake.

 

Surge is caused when you increase compressor side pressure to the point when it can no longer be maintained, then a temporary reverse flow takes effect. On our turbos, adding a chip increases the compressor pressure at a lower rpm, basically meaning you get more boost at the low end because you are fueling more. At that time, the compressor side is supplying more air than the engine is taking in. Our turbos can't maintain that pressure due to the design of the wheel and compressor housing, so the air has to go somewhere. Change one or the other and you can elminate most or all of the surge. The surge takes place on the compressor side, not the turbine side, which is why a different exhaust would have minimal effect on compressor surge.

I've personally run a chip with stock exhaust and stock turbo. I can tell you that towing, and driving up long hills or mountain passes could be a pain at times because the surge was so bad. Adding a bigger exhaust didn't change anything. With an open intake like the 6637 filter, the surge can easily be heard. But if you have the stock intake or a closed box like the AIS, the sound is muffled. You can watch surge on your boost gauge. The needle will bounce up and down rapidly. Only by replacing my turbo with a BB did the problem go away. You can cure surge with the ATS housing, and a WW will get rid of most of the surge. Without that, controlling surge by engine rpm's is the only way. Most surge happens starting around 1800 rpm's, with a load or driving uphill, and boost usually at 10-16 psi.

 

What are the mileage implications of adding a bigger exhaust? I understand more power, less EGT, MPG......???

 

Swapping the exhaust itself gave me no noticeable difference in mileage. Also performance didn't change. Just egt temps.

 

Something to remember, if you were to get 5" exhaust, 7.3L's tend to drone badly if not setup right with 5".

Check out my selection of exhausts at www.puredieselpower.com

 

thanks for all the help

 

Its the 4" that has the drone. No issues here with the drone. Just do a search on drone and compare the people who have drone and those who dont. Pocket you sound very knowledgable about the compressor surge, but you are missing this one. My truck and many other in stock form has not compressor surge. The only thing I changed on my truck that caused the surge was the exhaust and the intake. My chip had nothing to do with the condition. I then added the WW. I did not add my chip untill I felt comfortable enough without all the compressor surge. It did help eliminate the surge, but not all of it. Repou be prepared to do some type of turbo upgrade if you add an aftermarket exhaust. Someone else please chime in and end this debate. If I am wrong Pocket I will appologize.

 

Maybe you and I aren't talking about the same thing. Are you referring to the "whooooooshhhhhhhhhhhh" sound you get when your tranny up-shifts, kinda like a Darth Vader exhale? If so that's different than the surge I was describing.

 

I need a muffler, my system doesn't go over the axle and it's pretty much a straight shot to the tailpipe. Plenty of turbo whistle.




More pictures.
https://www.ford-trucks.com/user_gal...oid=91894&.jpg
https://www.ford-trucks.com/user_gal...oid=91896&.jpg
And I made some sound recordings as well.
https://www.ford-trucks.com/lc/lc.ph...d%2Findex.html