whats the stock pipe size after the cat,before the muffler? 2 1/4"?

 

2.5 on my 95.....up in the 1999+ i think they went to 3

 

kk thanks

 

Nope, they didn't go to 3" after the cat on any 94-01 Rams.

They had a 3" expansion on the last foot or two, right before the pipe exits behind the passenger tire, on 2000-2001 Rams.

3" going into the catalytic converter, 3" leaving the converter reduced to 2.5" about three inches later going to the muffler, 2.5" out of the muffler, and then the expansion to 3" right before exit.

Thats for 2000-2001 Rams. 1999 and before, it was two 2" pipes into converter, one 2.5" out of converter to muffler, one 2.5" out of muffler.

 

so on my 2001 if i went full 3 inch pipe i shouldnt lose much low end over stock right?

 

That seems an odd thing to do after the experiments I've recently run on my 95 5.9l. I wonder why they didn't go to a 3" cat back after moving to the 3" i/o cats. My impression of the 3" cat back w/ 3" i/o cat via seat of the pants dyno has been nothing but positive

 

Depends on how stock you are. If you still have the stock converter and a completely stock engine, not really. If you went to a performance muffler and high-flow catalytic converter, and no engine upgrades, you may lose a little low end.

I definitely wouldn't go any larger than 3".

Yes, I thought it was weird as well. If you like, I can show you pictures. I had a FM Super 44 and Magnaflow high-flow cat put in, but I didn't change any of the pipe sizes (yet).

 

Bone stock other than so called Mopar performance PCM and Fuel Performance kit which were installed when I bought the truck. Nothing yet that will affect CFM's and all that other than the exhaust tweaking.

I switched from stock cat to Magnaflow high flow 3" i/o cat replacing all remaining 2.5" pipe in the process w/ all 3". When I was using stock cat I had it set up similar to what it sounds like the newer OEM config is in that it went from the cats 2.5" out and short length of 2.5" pipe to a 3" tailpipe.

I've just been surprised by yours and others comments that the 3" could be too big. I wish I had gotten it dynoed now. Dyno runs are $$$ around here though. If I hadn't tried it myself I'd be the biggest skeptic out there but man it's sure fooling me if it isn't quite a little bit better all around now, ie better low RPM's and high RPM's, everywhere. With your and others comments I'm double guessing myself wondering if I'm one of those dweebs I always laugh at who talks themselves into believing some mod helped and it either didn't really help or even had a negative affect. I'd have to laugh if I've been fooling myself and any percieved gains I got were all in my head.

Per the calculators I was using I definitely agree that 3" is about where you'd expect to find the knee in the curve with with a stock engine.

It might be cool to see how OEM was but only if you have it handy.