Just thought I would post this in case anyone else was pondering it as well. I was wondering if deleting my cat would increase power/gas milage. I have a 2005 F250 CC Shortbed 4X4, 6.0 Powerstroke, automatic, 42,000 miles. It has a 5.5" DR lift with 35" Toyo AT's and stock 3:73 gearing. The truck already had an MBRP 4" turbo back exhaust with MBRP muffler and retained the stock cat. I removed the cat and put in the MBRP "Cat test" (straight pipe). By the way, took all of ten minutes for entire project. Prior to removing the cat, my truck consistantly got 14.8 mpg (using real math by the way). After removing the cat and installing the straight pipe, I tested two tanks of gas, driving the exact same route every day (work) that I did to calculate the prior milage calculations. It now consistantly gets 15.9 mpg. Power wise, it seems to have a tad bit more power throughout the RPM range, and the turbo seems to spool up a little quicker. Noise seems a little more throaty when you stand in it, and the turbo is just a hare louder. With windows rolled up, sounds exactly the same at any speed, no droan inside the cab etc.... Very pleased, and easy to re-install the cat if needed in the future. Best $59.00 I've ever spent!!!

 

Thanks, looks like I will order the MBRP with Test pipe.

 

delete the muffler while your at itthe turbo is a very effective muffler it wil pick up a few hp

 

Was the cat delete the only mod you made while checking your results? That's a pretty impressive jump for just deleting the cat. Wish I had know it would make that big a difference 242,000 miles ago.

 

i noticed the same kind of result, i get 20 at about 68 mph on the highway, best before was around 18.5

Bruno

 

Yep, that's all I did. I was very curious, so I made sure what exactly my gas milage was prior to the cat delete. It was always 14.8 on the last five tanks of gas. I drove the exact same route, same traffic conditions, and no weather (wind, rain etc). Kept the truck between 65 and 70 mph (1500-1800 rpm) I then removed the cat and conducted the same test with two tanks, and magic....both tanks exactly 15.9.......Can't beat that!!! Should pay for itself in a few tanks. I was contemplating removing the muffler, but my buddies truck has an annoying drone in the cab with his muffler removed.

 

also thinking about removing muffler, but i have a 5" system

Bruno

 

Would anyone think that the same result can be achieved by deleting the cat on a stock exhaust system (like mine)?

 

I would think some type of gain could be had. Obviously it is very restrictive. I had a 93 460 gasser and deleted the cat. What a difference on that pig!!!! Three miles to the gallon, and I swear it felt like about 50 horsepower. Alot louder though on the gasser.

 

Would deleting it on a stock system have any negative impact on the stock muffler? Also, any ideas on where to get the 'test' pipe?

 

When I ordered my 02 and received it, I asked the dealer about the cat. He said all CA trucks and standards had them. I contemplated removing it, but never got around to it. Excuse me while I go kick myself now.

If I try this now and it works I'm gonna be pissed for a long time.

 

I installed a 4" Mbrp turbo back system on my '07. When the kit came in the delete pipe was in another box and did not make it.
I got it on the next day, put 4 tanks thru it before i got around to laying under it again. I've tracked every tank of fuel since new. After installation WITH cat gained 1 to1.25 mpg over stock AFTER cat delete did not see and difference in mpg?

Sure sounds better now.

 

Thank you. Now I can sleep tonight.

 

I got my test pipe at my dealer. I have the test pipe and no muffler, very sweet sound and not loud at all in the cab. (05 F350 6.0)

 

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the stock muffler is more restrictive than the cat but by deleting both your truck will get louder but more mpg's. There are some easy mods for either modifying your stock exhaust to eitehr straight pipe it or install a straight thru flow thru muffler. do a search in the 6.0 forum and the guys there have done plenty, w/ pics to.