So i have the 97 f250 heavy duty with 7.3l turbo diesel. I wanted to get the full 4in exhaust from the turbo back so i went to a exhaust shop. They said they dont make a full 4in cause the down pipe flatens out and runs down the fire wall after the turbo. Is it true that i cant get a full 4in?

 

You can have one made but it takes alot of work to get it to fit. Most kits have a 3in downpipe.

 

You won't get a true full 4" all the way from the turbo to the tail pipe. The factory downpipe is flat as a pancake because there is no room between the motor and the firewall. Thus most of the kits out there for our trucks are 3" round downpipes that transition to 4" by the tranny. 3" round downpipe is more than your stock downpipe so just run a 4" exhaust with a 3" downpipe.

If you really want a 4" downpipe then you need to do a good size body lift or modify your firewall pretty good.

 

3" is a tight fit and takes "body modifacation" as is to get the round 3" to fit, if you go with 3" down pipe to a 4" exhaust, youll be fine, thats what most of us run anyway

 

A 3" down pipe does not take any modifications they are tight but certain pipes will fit.

 

I would say for the most part, most 3" downpipes need a little modification to the firewall seam. There are always some that don't need this but I wouldn't go as far to say that there is no modifications necessary at all..

 

that three inch down pipe should slip between motor and firewall with no mods. u can just remove one bellhousing bolt and should be able to wiggle it down . i have done two of these on 95 and 96 powerstrokes. i cut the firewall seam on my 95 and it fit on. my brothers 96 i found i could just remove the bellhousing bolt and do no cutting

 

I have done 3 and all needed a crowbar and some leverage to make room for the aftermarket downpipe. A portapower is even easier.