I have a few exhaust questions that I need answered as soon as possible.

I have a 2001 3.9L V6. I cut off the muffler, left the cat on, and am going to straight pipe.

What's the stock exhaust diameter?
I tried to measure and it seems like it's 2.5" off the cat, but then close to 3" from behind the muffler. However, when I measured, it's not exactly 3".

What exhaust diameter would give me the best sound/performance without sacrificing power?

And one more thing. I cut the muffler off after the cat, and when I started it up that day, the sound was very loud, "powerful", and kind of deep. Well, I ran it like that for a few days, and as the days went on, the quiter the sound got. Do you know the reason for this?

Thanks!

 

The cat is clogged! And you need to post your question in the Dakota section of this forum

 

you probity just got used to the sound. happens with my monte carlo all the time.

 

Thanks for the suggestion! Should I just cut it off and buy a new one?

Oh, and do you think I would get more answers over there? I have a 1500, but I believe the 3.9 Dakotas have the same system.

 

That's what I was wondering. I was just hoping nothing got screwed up. But I am definately going to check the cat.

 

yes, post in that section. and as far as i know. the 3.9's have the same issue with the intake and cat. as the 5.2 and 5.9's do.