looking to get a downpipe

[dieselpower65]

What is the best downpipe for my 05 f350? should i go with a 3.5 or 4 inch downpipe and what brand?

[cartmanea]

If you really think you need one, go with a 3.5" MBRP. It is HUGE compared to the OEM downpipe and doesn't have the clearance issues of the 4". You won't notice much if any performance improvement though. The '05 downpipe is smaller, but doesn't have the crimped/flattened sections the earlier ones had.

[colo_dually]

If you are only doing a downpipe to the CAT, you'll want the 3.5". The 4" DPs that I have found, all are included with 4" turboback systems, and delete the CAT.

I saw a little decrease in EGT's going to the 3.5" I have on mine, and it still has the CAT.

[dieselpower65]

well i have a proggramer and i have 4inch piping from the cat back and my cat is hollowed out so i figured i should get a dp and finish my exhaust

[dhetrick2]

IMO I wouldn't waste the money, I bought the MBRP 4" turbo back exhaust, installed the cat back first because of the pita replacing the dp and drove it that way for a couple months. Sounded great but didn't see much other difference. Then I had the dp installed when the dealership had my engine out for bed pan seals. I didn't see much change in the egt and now have problems with the gasket between the dp and cat. Also ever since then my fuel mileage has seemed to have gone down 1 - 2 mpg. Just my opinion and experience.

[dieselpower65]

Originally Posted by dhetrick2

IMO I wouldn't waste the money, I bought the MBRP 4" turbo back exhaust, installed the cat back first because of the pita replacing the dp and drove it that way for a couple months. Sounded great but didn't see much other difference. Then I had the dp installed when the dealership had my engine out for bed pan seals. I didn't see much change in the egt and now have problems with the gasket between the dp and cat. Also ever since then my fuel mileage has seemed to have gone down 1 - 2 mpg. Just my opinion and experience.

oh wow you actually lost mpgs from it that sucks. sounds like one big headache to me.

[dieselpower65]

Originally Posted by dhetrick2

IMO I wouldn't waste the money, I bought the MBRP 4" turbo back exhaust, installed the cat back first because of the pita replacing the dp and drove it that way for a couple months. Sounded great but didn't see much other difference. Then I had the dp installed when the dealership had my engine out for bed pan seals. I didn't see much change in the egt and now have problems with the gasket between the dp and cat. Also ever since then my fuel mileage has seemed to have gone down 1 - 2 mpg. Just my opinion and experience.

thanks for the input

[cartmanea]

I seriously doubt the downpipe made you lose mileage. More likely, they reflashed your truck to the latest strategy after the engine work and the newer one gets poor mileage.

[dhetrick2]

That was my first thought, the service writer claimed they didn't do a reflash and that it would have been in the tech's notes if they did but who knows. The current stratagy is VXC7H3 which I believe is an older one. I have gained some milage back with my custom tunes.

[Davey~do]

Originally Posted by dieselpower65

oh wow you actually lost mpgs from it that sucks. sounds like one big headache to me.

I went with a MBRP turbo-back as well and lost a bit of mileage with the same flash. I lost my mileage because my foot got about 2-1/2 lbs. heavier though

Just go with the 3.5" downpipe. Going to 4" wont make a bit of difference other than being harder to install. Oh yeah. Something I found out when I did mine on a Sunday night and having to go to work the next morning.... make sure you have a saws-all with a LONG blade. The one that most likely came with your saw when you purchased it wont quite make it......