Science?

One of the basic tenets of fluidics is that maximum flow in a system will be determined by the most restrictive element in that system.

 

The system changes after the cat. You can alter the flow of the system by changing the components. The max flow after the stock muffler would be lower than the max flow after a higher flowing muffler.

This is assuming that the stock muffler is more restrictive than an aftermarket one:

If you measure 800cfm after the cat, I would assume that it would be less than 800 after the stock muffler because you have added another bottleneck. You can improve that rate, but it would never surpass 800.

So your statement does nothing to fault my explanation.

 

Actually, you've mistaken my intent, which was to bring a measure of clarity to this thread's discussion of intake & exhaust flow through a Cummins... besides, I'm still not sure what your explanation is.

 

A less restrictive muffler will improve the flow.

 

I had a flowmaster on my truck, 4 inch exhaust to flowmaster then 4 inch duals, sounded great, i put that on to solve the drone issue i had when towing straight piped. Nice tone!

 

I've had the same experience as "lightening ram" When I put a less restrictive exhaust on my 2002, I actually lost bottom-end performance. The turbo wouldn't spool up as fast. I've read about it happening to a couple other guys too. I'm keeping my exhaust stock until my mods force me to upgrade.

 

I went to the rokktech website, and that probably is the way to go. I have a friend who's hubby has a powerjoke, he can't stand being out done in anything. Everytime I add something to my CTD, he buys something else for the Ford. He's more interrested in doing burnouts, i wouldn't waste the wear and tear on my tires and clutch. It's enought for me that everytime we all go riding, I make sure I am front so I don't have to wait on him.
I guess since I already have the intake, I should leave it alone, add a muffler for now just to make it sound better. I do un-hook the trailer every once in a while and take it out on a saturday night. I will mess with any GM or Ford I end up beside. Gut the cat once it's out of warranty, and I have been through several inspections so I know whether they check to make sure it's still there or not.
It will probably help to clean my filter, the truck has only 3700 miles on it, but I did buy the intake used from a friend of mine who installed it on his wife's truck, and ending up taking it off since she complained about the extra turbo noise. My restriction guage is still in the green, but it has moved. I don't think my friend ran the intake long, but who knows. Couldn't pass up on the price though. $150 and it's one of the brute force intakes with the washable non oiled filters.