What would be the best diameter pipe to straight pipe my truck with? It is a stock 2001 cummins. Also where should I straight pipe it from. I guess I want to know what would be the loudest and best sounding?

 

Cut the pipe right before the cat and after the muffler and replace with a new 3in piece of pipe the stock tail pipe is 3in if you get a 3in pipe be sure to get 3 to 3in adapters or have the ends swelled to fit over the two ends.

 

I have mine exactly the way SmokinDodge described and love the way it sounds.

If your at all concerned about how loud it will be, cut the muffler off first but leave the resonator. Seems to work for alot of people who are concerned about noise/legality issues

 

I have mine straight piped from turbo to tail, 4". It's definitely loud and I like the tone.

If you are really looking for sound past that, put in an aftermarket air intake (discussed all over these boards) and get rid of the silencer ring!

Matt

 

I had exhaust pros, which I believe they have some nationwide stores, take it just b4 the cat and right after the muffler took a 1/2 hour and only cost $100.
I love the sound especially the turbo sound through the exhaust, the chirp, sound like a huge tractor or semi and I love it

 

cut everything out buy a piece of three inch on the tail put a 4in or 5 tip it will make a little deeper.

 

just the tip 4 0r 5 inch? how long 1 or 2 feet? lust to the bend? that will give me more of a throaty deep sound? TIA

 

take the whole stock system out and put a 5 inch downpipe back system on with a 4 inch downpipe, you wont be upset
then let the bombing begin

 

You must understand that with this question its ALL personal preference. Its just something you will have to experience for yourself to find out what works for you. I too was wondering what I could get out of my truck with no muffler. Sounded great. But I couldnt resist trying it without the resonator so I had that removed too. Now it sounds really nice if you like to hear the turbo but for the gain in sound I have also aquired an annoying resonating around 2200 RPM. Very annoying when towing! Now I want a 4" system with a straight through muffler so I keep the EGT's where they are and retain a lot of the sound but eliminate the resonating. Also you need to make sure you match your exhaust size with you power output. If you go to big you will actually decrease in power. I cant remember the figures so do a little research with some shops that can give you accurate info on what you should do before buying anything.

 

Yep, K is right on that one. Unless you are around 450-500 hp at the rear wheels, a 5" system will actually decrease the trucks power. A 4" system is the best bet, until your bombing brings your rig up to 500hp.

Good luck,
Hunter

 

I've got 4" straight piped dumped in front of the rear axle. It is incredibly LOUD. But it sounds just down right wicked when your on it.