I got a 93 - F250 Factory Garrett Turbo with the 2 1/4" exhaust and am seriously thinking about going to the 3" ATS exhaust. I have already opened up the intake by going with a K&N RU-250 Turbo Filter and it completely eliminated the vacuum I used to see on the suction side of my turbo. I still need to bring the new filter into the fresh air stream, for now I just mounted it off the old turbo inlet housing where the fresh air duct used to connect. What I lost in milage due to the warm air the engine gets I seem to have gained in milage due to the elimination of the pressure drop so my overall milage is pretty much the same as it was.

A few questions on the exhaust upgrade:

1, For those who have done the 3" exhaust upgrade, how tight is the new 3" housing to the firewall on the F250. Is there going to be enough room to get some sort of insulation between the firewall of the truck and the housing and downpipe. (I have no intention of raising my truck to do this, I like the factory height, there is also the legality issue of raising the truck which I don't want to have to deal with.)

2, Has anybody got some good, documented milage improvements as a result of going to the 3" ATS exhaust. (Would it be to much to expect a milage increase of 1.5 to 2.0 miles per gallon, assuming I don't become a leadfoot after the upgrade like some of the guys on this Website)

 

1. lifting your truck isnt illegal at all.
2. you will have a lead foot.
3. 2 mpg is reasonable.
4. you have to cut the firewall seam and hammer a little, but with a sawzall its real easy.
5. K&N filters aren't anything that they are hyped up to be, they just dust your engine real bad. Get a purolator and do the cold ram air mod like Dave or ziggster did.

Edit:
6. the best way to bend the firewall after cutting it is to get a scissor style jack found in many small cars and chebby trucks and put it in there against the back of the block or bellhousing and then crank away.

 

Thanks Rawpower, I see you have been around a while on this site.

It sounds like you really need to get a little rough with the firewall to make the the 3" ATS Exhaust and housing fit and get a bit of clearance for some heat shielding insulation as well. It sure looks tight to me even with the 2 1/4" exhaust.

Our local law enforcement does not treat guys with custom raise jobs kindly if you get caught. Nabbed a mechanic friend of mine a while back for jacking his F250 a few inches, so I am not taking a chance on going down that road.

 

hmm thats weird. i guess if its just thrown together then thats a no-no, which in my opinion, should be heavily fined if its deemed unsafe. I build stuff for my truck, but only if i know i can do it right and safely- at least better and safer than stock or aftermarket parts that im trying to immitate... If that is the case, then aftermarket parts that are 50-state legal should do you fine. but that means adding a body lift, and im not really partial to body lifts- at all.

yeah you do have to get a little rough with the firewall, but not too much. its nothing to worry about. as long as you think and use common sense it will all come out OK

Edit: where are you located?

 

Located in British Columbia, Canada.

 

oh. K&N is fine for you then since yall dont have much dust up there. down here in texas a K&N is bad for a diesel since it lets in so much dust compared to a paper filter.

 

A 1" body lift is plenty of room for the 3" downpipe.
I did a 2" body lift on my 86 250 4x4 when I was getting ready to install it.
I have plenty of room for a 4 or 5 inch downpipe now.

The first couple of tanks of fuel will have lower fuel mileage than you are getting now.
You will not be able to resist temptation.