exhaust questions

[CrewCab350]

Hey guys, I am new to the site but have a quick question about my truck. I have a June of 98 f350 dually with a 7.3. I took the exhaust off from the cat back and replaced it with strait 4 inch from a local muffler shop who had some left over pipe, no cat or muffler. I feel like I lost a little power pulling but my buddy did the same thing and no power loss. What might be going on, should I buy a down pipe? Thanks.

[JJR]

I had similar results with my early 99. I tried a stock downpipe and a 4 inch downpipe and it made no difference. What you need is a custom tuned chip to utilize the air flow improvement.

[CrewCab350]

Where is a good place to get a custom chip? The truck is totally stock with 282,000 miles.

[Degnol]

Is there a huge benefit to replacing the downpipe? I mean the exhaust outlet on the turbo is 3.5", right? Has anyone just run 4" from the downpipe back?
I am a newb-rube, so go easy on an old guy

[dannanw]

just taking out the cat and muff on the sock size will do the same thing, the down pipe on our E99's is 3in, alll you will gain is lower egt's from bigger down pipe. and if you have the stock intake then you prob wont feel much diffrence in power cause the stock air box is very restritive. I would say do a DIY intake and see it that helps.

[Degnol]

Thanks! I do have the Ford AIS so maybe that and the muffler delete will help. I don't have a cat.
Pulling a 7K load, my egts only hit about 700*and come down really fast to a normal of 4-500*

[dannanw]

yea a down pipe only helps lower egt's. next step for more hp and some MPG (if you can pullit off) is a chip.