I ripped my entire system out, save the down pipe and replaced it with 3" EMT conduit. I dumped it behind the cab.

With that and my K&N, will I over-speed my turbo, if I replace the stock down pipe?

 

well i can tell you this, on a gas job and efficient converter will drop the gas readings(5 of them) about 45% is the threshold. but to do this you must drill a hole before the cat and test @ the tail pipe.
and you need a 5 gas analyser. or an infered temp gun should see a difference before and after. not sure of the temps though.... too many variables there.

but if the connections are all rusty, i would guess that it was not done. most people( contractors) leave them alone. till they are broken,

 

Just a quick update on my experience....

Yes, I have better throttle response with the short straight pipe.

My connections were all rusted, including the three inches of pipe inside the expanded pipe going to the muffler..thus the three hours to drop the cat.... Alas, it was empty!!

I suppose that a person could just drop the pipe off of the downpipe connection and take a bar and/or welding wire and work it towards/into the cat to see if it meets restrictions or not.

 

I have a 97 PSD and today i had a hard time disconnecting the cat from the stright pipe after the cat. has anyone else have this problem if so how did you disconnect the cat?

 

I used a die grinder and cut slots up the outer pipe to help get it out. That work for me. Good luck!

 

I used a sawsall.

 

I agree w/ Itfox...

After using pb blaster and fighting w/ the pipe, I ended up cutting 4 slots up the pipe about 1 1/2 inches and expanding it away from the cat pipe. Notice the locating pin on the cat pipe to exhaust... you can't twist the cat unless you get clearance for the pin to rotate..

 

Have 02 F350 7.3. With no cat straight from the factory.

 

A torch worked great on mine.

 

My 95 was about as hard to pull apart as any, if you want to keep the stuff where you can put them back together. At least without a welder LOL...

Once I get the U bolt off the slip fitting I find that by shooting the fittings with some kind of penetrate really good, instead of just trying to man handle this tight fitting straight apart from each other, its best to work the fitting back and forth, up and down as best you can. Get this action going in a circular motion soon as you get some of your sideways motion bent to as much as possible.

This will help widen the coined in spot where the clamp hucked the pipe into itself and bending this out by rolling the fitting around a little and as agressive as possible will loosen the fitting right up. Get ugly with this too will work even better. Just think about all the EPA ****'s your going to "T" off by removing, gutting and or moding this system they are so proud of. With that one thought alone drove me to getting mine apart just to "T" off the EPA ****'s LOL...

Now if your not going to replace this with a delete pipe once removed, then make sure to sand and or buff the slip fit really good before going back together. Going back together with these has always been harder than taking them apart if you don't clean them up good.